Merge branch 'origin/proposed/3.0' into master

docs/source/conf.py

@@ -0,0 +1,300 @@
+# -*- coding: utf-8 -*-
+#
+# flake8 documentation build configuration file, created by
+# sphinx-quickstart on Tue Jan 19 07:14:10 2016.
+#
+# This file is execfile()d with the current directory set to its
+# containing dir.
+#
+# Note that not all possible configuration values are present in this
+# autogenerated file.
+#
+# All configuration values have a default; values that are commented out
+# serve to show the default.
+
+import sys
+import os
+
+# If extensions (or modules to document with autodoc) are in another directory,
+# add these directories to sys.path here. If the directory is relative to the
+# documentation root, use os.path.abspath to make it absolute, like shown here.
+#sys.path.insert(0, os.path.abspath('.'))
+
+# -- General configuration ------------------------------------------------
+
+# If your documentation needs a minimal Sphinx version, state it here.
+needs_sphinx = '1.3'
+
+# Add any Sphinx extension module names here, as strings. They can be
+# extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
+# ones.
+extensions = [
+    'sphinx.ext.autodoc',
+    'sphinx.ext.doctest',
+    'sphinx.ext.intersphinx',
+    'sphinx.ext.todo',
+    'sphinx.ext.coverage',
+    'sphinx.ext.viewcode',
+    'sphinx-prompt',
+]
+
+# Add any paths that contain templates here, relative to this directory.
+templates_path = ['_templates']
+
+# The suffix(es) of source filenames.
+# You can specify multiple suffix as a list of string:
+# source_suffix = ['.rst', '.md']
+source_suffix = '.rst'
+
+# The encoding of source files.
+#source_encoding = 'utf-8-sig'
+
+# The master toctree document.
+master_doc = 'index'
+
+# General information about the project.
+project = u'flake8'
+copyright = u'2016, Ian Cordasco'
+author = u'Ian Cordasco'
+
+import flake8
+# The version info for the project you're documenting, acts as replacement for
+# |version| and |release|, also used in various other places throughout the
+# built documents.
+#
+# The short X.Y version.
+version = flake8.__version__
+# The full version, including alpha/beta/rc tags.
+release = flake8.__version__
+
+rst_epilog = """
+.. |Flake8| replace:: :program:`Flake8`
+"""
+
+# The language for content autogenerated by Sphinx. Refer to documentation
+# for a list of supported languages.
+#
+# This is also used if you do content translation via gettext catalogs.
+# Usually you set "language" from the command line for these cases.
+language = None
+
+# There are two options for replacing |today|: either, you set today to some
+# non-false value, then it is used:
+#today = ''
+# Else, today_fmt is used as the format for a strftime call.
+#today_fmt = '%B %d, %Y'
+
+# List of patterns, relative to source directory, that match files and
+# directories to ignore when looking for source files.
+exclude_patterns = []
+
+# The reST default role (used for this markup: `text`) to use for all
+# documents.
+#default_role = None
+
+# If true, '()' will be appended to :func: etc. cross-reference text.
+#add_function_parentheses = True
+
+# If true, the current module name will be prepended to all description
+# unit titles (such as .. function::).
+#add_module_names = True
+
+# If true, sectionauthor and moduleauthor directives will be shown in the
+# output. They are ignored by default.
+#show_authors = False
+
+# The name of the Pygments (syntax highlighting) style to use.
+pygments_style = 'sphinx'
+
+# A list of ignored prefixes for module index sorting.
+#modindex_common_prefix = []
+
+# If true, keep warnings as "system message" paragraphs in the built documents.
+#keep_warnings = False
+
+# If true, `todo` and `todoList` produce output, else they produce nothing.
+todo_include_todos = True
+
+
+# -- Options for HTML output ----------------------------------------------
+
+# The theme to use for HTML and HTML Help pages.  See the documentation for
+# a list of builtin themes.
+html_theme = 'sphinx_rtd_theme'
+
+# Theme options are theme-specific and customize the look and feel of a theme
+# further.  For a list of options available for each theme, see the
+# documentation.
+#html_theme_options = {}
+
+# Add any paths that contain custom themes here, relative to this directory.
+#html_theme_path = []
+
+# The name for this set of Sphinx documents.  If None, it defaults to
+# "<project> v<release> documentation".
+#html_title = None
+
+# A shorter title for the navigation bar.  Default is the same as html_title.
+#html_short_title = None
+
+# The name of an image file (relative to this directory) to place at the top
+# of the sidebar.
+#html_logo = None
+
+# The name of an image file (within the static path) to use as favicon of the
+# docs.  This file should be a Windows icon file (.ico) being 16x16 or 32x32
+# pixels large.
+#html_favicon = None
+
+# Add any paths that contain custom static files (such as style sheets) here,
+# relative to this directory. They are copied after the builtin static files,
+# so a file named "default.css" will overwrite the builtin "default.css".
+# html_static_path = ['_static']
+
+# Add any extra paths that contain custom files (such as robots.txt or
+# .htaccess) here, relative to this directory. These files are copied
+# directly to the root of the documentation.
+#html_extra_path = []
+
+# If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
+# using the given strftime format.
+#html_last_updated_fmt = '%b %d, %Y'
+
+# If true, SmartyPants will be used to convert quotes and dashes to
+# typographically correct entities.
+#html_use_smartypants = True
+
+# Custom sidebar templates, maps document names to template names.
+#html_sidebars = {}
+
+# Additional templates that should be rendered to pages, maps page names to
+# template names.
+#html_additional_pages = {}
+
+# If false, no module index is generated.
+#html_domain_indices = True
+
+# If false, no index is generated.
+#html_use_index = True
+
+# If true, the index is split into individual pages for each letter.
+#html_split_index = False
+
+# If true, links to the reST sources are added to the pages.
+#html_show_sourcelink = True
+
+# If true, "Created using Sphinx" is shown in the HTML footer. Default is True.
+#html_show_sphinx = True
+
+# If true, "(C) Copyright ..." is shown in the HTML footer. Default is True.
+#html_show_copyright = True
+
+# If true, an OpenSearch description file will be output, and all pages will
+# contain a <link> tag referring to it.  The value of this option must be the
+# base URL from which the finished HTML is served.
+#html_use_opensearch = ''
+
+# This is the file name suffix for HTML files (e.g. ".xhtml").
+#html_file_suffix = None
+
+# Language to be used for generating the HTML full-text search index.
+# Sphinx supports the following languages:
+#   'da', 'de', 'en', 'es', 'fi', 'fr', 'hu', 'it', 'ja'
+#   'nl', 'no', 'pt', 'ro', 'ru', 'sv', 'tr'
+#html_search_language = 'en'
+
+# A dictionary with options for the search language support, empty by default.
+# Now only 'ja' uses this config value
+#html_search_options = {'type': 'default'}
+
+# The name of a javascript file (relative to the configuration directory) that
+# implements a search results scorer. If empty, the default will be used.
+#html_search_scorer = 'scorer.js'
+
+# Output file base name for HTML help builder.
+htmlhelp_basename = 'flake8doc'
+
+# -- Options for LaTeX output ---------------------------------------------
+
+latex_elements = {
+# The paper size ('letterpaper' or 'a4paper').
+#'papersize': 'letterpaper',
+
+# The font size ('10pt', '11pt' or '12pt').
+#'pointsize': '10pt',
+
+# Additional stuff for the LaTeX preamble.
+#'preamble': '',
+
+# Latex figure (float) alignment
+#'figure_align': 'htbp',
+}
+
+# Grouping the document tree into LaTeX files. List of tuples
+# (source start file, target name, title,
+#  author, documentclass [howto, manual, or own class]).
+latex_documents = [
+    (master_doc, 'flake8.tex', u'flake8 Documentation',
+     u'Ian Cordasco', 'manual'),
+]
+
+# The name of an image file (relative to this directory) to place at the top of
+# the title page.
+#latex_logo = None
+
+# For "manual" documents, if this is true, then toplevel headings are parts,
+# not chapters.
+#latex_use_parts = False
+
+# If true, show page references after internal links.
+#latex_show_pagerefs = False
+
+# If true, show URL addresses after external links.
+#latex_show_urls = False
+
+# Documents to append as an appendix to all manuals.
+#latex_appendices = []
+
+# If false, no module index is generated.
+#latex_domain_indices = True
+
+
+# -- Options for manual page output ---------------------------------------
+
+# One entry per manual page. List of tuples
+# (source start file, name, description, authors, manual section).
+man_pages = [
+    (master_doc, 'flake8', u'flake8 Documentation',
+     [author], 1)
+]
+
+# If true, show URL addresses after external links.
+#man_show_urls = False
+
+
+# -- Options for Texinfo output -------------------------------------------
+
+# Grouping the document tree into Texinfo files. List of tuples
+# (source start file, target name, title, author,
+#  dir menu entry, description, category)
+texinfo_documents = [
+    ('index', 'Flake8', u'Flake8 Documentation', u'Tarek Ziade',
+     'Flake8', 'Code checking using pycodestyle, pyflakes and mccabe',
+     'Miscellaneous'),
+]
+
+# Documents to append as an appendix to all manuals.
+#texinfo_appendices = []
+
+# If false, no module index is generated.
+#texinfo_domain_indices = True
+
+# How to display URL addresses: 'footnote', 'no', or 'inline'.
+#texinfo_show_urls = 'footnote'
+
+# If true, do not generate a @detailmenu in the "Top" node's menu.
+#texinfo_no_detailmenu = False
+
+
+# Example configuration for intersphinx: refer to the Python standard library.
+intersphinx_mapping = {'python': ('https://docs.python.org/3.4', None)}

docs/source/faq.rst

@@ -0,0 +1,56 @@
+============================
+ Frequently Asked Questions
+============================
+
+When is Flake8 released?
+========================
+
+|Flake8| is released *as necessary*. Sometimes there are specific goals and
+drives to get to a release. Usually, we release as users report and fix
+bugs.
+
+
+How can I help Flake8 release faster?
+=====================================
+
+Look at the next milestone. If there's work you can help us complete, that
+will help us get to the next milestone. If there's a show-stopping bug that
+needs to be released, let us know but please be kind. |Flake8| is developed
+and released entirely on volunteer time.
+
+
+What is the next version of Flake8?
+===================================
+
+In general we try to use milestones to indicate this. If the last release
+on PyPI is 3.1.5 and you see a milestone for 3.2.0 in GitLab, there's a
+good chance that 3.2.0 is the next release.
+
+
+Why does Flake8 use ranges for its dependencies?
+================================================
+
+|Flake8| uses ranges for mccabe, pyflakes, and pycodestyle because each of
+those projects tend to add *new* checks in minor releases. It has been an
+implicit design goal of |Flake8|'s to make the list of error codes stable in
+its own minor releases. That way if you install something from the 2.5
+series today, you will not find new checks in the same series in a month
+from now when you install it again.
+
+|Flake8|'s dependencies tend to avoid new checks in patch versions which is
+why |Flake8| expresses its dependencies roughly as::
+
+    pycodestyle >= 2.0.0, < 2.1.0
+    pyflakes >= 0.8.0, != 1.2.0, != 1.2.1, != 1.2.2, < 1.3.0
+    mccabe >= 0.5.0, < 0.6.0
+
+This allows those projects to release patch versions that fix bugs and for
+|Flake8| users to consume those fixes.
+
+
+Should I file an issue when a new version of a dependency is available?
+=======================================================================
+
+**No.** The current Flake8 core team (of one person) is also
+a core developer of pycodestyle, pyflakes, and mccabe. They are aware of
+these releases.

docs/source/glossary.rst

@@ -0,0 +1,56 @@
+.. _glossary:
+
+================================================
+ Glossary of Terms Used in Flake8 Documentation
+================================================
+
+.. glossary::
+    :sorted:
+
+    formatter
+        A :term:`plugin` that augments the output of |Flake8| when passed
+        to :option:`flake8 --format`.
+
+    plugin
+        A package that is typically installed from PyPI to augment the
+        behaviour of |Flake8| either through adding one or more additional
+        :term:`check`\ s or providing additional :term:`formatter`\ s.
+
+    check
+        A piece of logic that corresponds to an error code. A check may
+        be a style check (e.g., check the length of a given line against
+        the user configured maximum) or a lint check (e.g., checking for
+        unused imports) or some other check as defined by a plugin.
+
+    error
+    error code
+        The symbol associated with a specific :term:`check`. For example,
+        pycodestyle implements :term:`check`\ s that look for whitespace
+        around binary operators and will either return an error code of
+        ``W503`` or ``W504``.
+
+    warning
+        Typically the ``W`` class of :term:`error code`\ s from pycodestyle.
+
+    class
+    error class
+        A larger grouping of related :term:`error code`\ s. For example,
+        ``W503`` and ``W504`` are two codes related to whitespace. ``W50``
+        would be the most specific class of codes relating to whitespace.
+        ``W`` would be the warning class that subsumes all whitespace
+        errors.
+
+    pyflakes
+        The project |Flake8| depends on to lint files (check for unused
+        imports, variables, etc.). This uses the ``F`` :term:`class` of
+        :term:`error code`\ s reported by |Flake8|.
+
+    pycodestyle
+        The project |Flake8| depends on to provide style enforcement.
+        pycodestyle implements :term:`check`\ s for :pep:`8`. This uses the
+        ``E`` and ``W`` :term:`class`\ es of :term:`error code`\ s.
+
+    mccabe
+        The project |Flake8| depends on to calculate the McCabe complexity
+        of a unit of code (e.g., a function). This uses the ``C``
+        :term:`class` of :term`error code`\ s.

docs/source/index.rst

@@ -0,0 +1,131 @@
+.. flake8 documentation master file, created by
+   sphinx-quickstart on Tue Jan 19 07:14:10 2016.
+   You can adapt this file completely to your liking, but it should at least
+   contain the root `toctree` directive.
+
+===============================================
+ Flake8: Your Tool For Style Guide Enforcement
+===============================================
+
+Quickstart
+==========
+
+.. _installation-guide:
+
+Installation
+------------
+
+To install |Flake8|, open an interactive shell and run:
+
+.. code::
+
+    python<version> -m pip install flake8
+
+If you want |Flake8| to be installed for your default Python installation, you
+can instead use:
+
+.. code::
+
+    python -m pip install flake8
+
+.. note::
+
+    It is **very** important to install |Flake8| on the *correct* version of
+    Python for your needs. If you want |Flake8| to properly parse new language
+    features in Python 3.5 (for example), you need it to be installed on 3.5
+    for |Flake8| to understand those features. In many ways, Flake8 is tied to
+    the version of Python on which it runs.
+
+Using Flake8
+------------
+
+To start using |Flake8|, open an interactive shell and run:
+
+.. code::
+
+    flake8 path/to/code/to/check.py
+    # or
+    flake8 path/to/code/
+
+.. note::
+
+    If you have installed |Flake8| on a particular version of Python (or on
+    several versions), it may be best to instead run ``python<version> -m
+    flake8``.
+
+If you only want to see the instances of a specific warning or error, you can
+*select* that error like so:
+
+.. code::
+
+    flake8 --select E123,W503 path/to/code/
+
+Alternatively, if you want to *ignore* only one specific warning or error:
+
+.. code::
+
+    flake8 --ignore E24,W504 path/to/code/
+
+Please read our user guide for more information about how to use and configure
+|Flake8|.
+
+FAQ and Glossary
+================
+
+.. toctree::
+    :maxdepth: 2
+
+    faq
+    glossary
+
+User Guide
+==========
+
+All users of |Flake8| should read this portion of the documentation. This
+provides examples and documentation around |Flake8|'s assortment of options
+and how to specify them on the command-line or in configuration files.
+
+.. toctree::
+    :maxdepth: 2
+
+    user/index
+
+Plugin Developer Guide
+======================
+
+If you're maintaining a plugin for |Flake8| or creating a new one, you should
+read this section of the documentation. It explains how you can write your
+plugins and distribute them to others.
+
+.. toctree::
+    :maxdepth: 2
+
+    plugin-development/index
+
+Contributor Guide
+=================
+
+If you are reading |Flake8|'s source code for fun or looking to contribute,
+you should read this portion of the documentation. This is a mix of documenting
+the internal-only interfaces |Flake8| and documenting reasoning for Flake8's
+design.
+
+.. toctree::
+    :maxdepth: 2
+
+    internal/index
+
+Release Notes and History
+=========================
+
+.. toctree::
+    :maxdepth: 2
+
+    release-notes/index
+
+General Indices
+===============
+
+* :ref:`genindex`
+* :ref:`Index of Documented Public Modules <modindex>`
+* :ref:`Glossary of terms <glossary>`

docs/source/internal/checker.rst

@@ -0,0 +1,70 @@
+====================
+ How Checks are Run
+====================
+
+In |Flake8| 2.x, |Flake8| delegated check running to pep8. In 3.0 |Flake8|
+takes on that responsibility. This has allowed for simpler
+handling of the ``--jobs`` parameter (using :mod:`multiprocessing`) and
+simplified our fallback if something goes awry with concurency.
+At the lowest level we have a |FileChecker|. Instances of |FileChecker| are
+created for *each* file to be analyzed by |Flake8|. Each instance, has a copy
+of all of the plugins registered with setuptools in the ``flake8.extension``
+entry-point group.
+
+The |FileChecker| instances are managed by an instance of |Manager|. The
+|Manager| instance handles creating sub-processes with
+:mod:`multiprocessing` module and falling back to running checks in serial if
+an operating system level error arises. When creating |FileChecker| instances,
+the |Manager| is responsible for determining if a particular file has been
+excluded.
+
+
+Processing Files
+----------------
+
+Unfortunately, since |Flake8| took over check running from pep8/pycodestyle,
+it also had to take over parsing and processing files for the checkers
+to use. Since it couldn't reuse pycodestyle's functionality (since it did not
+separate cleanly the processing from check running) that function was isolated
+into the :class:`~flake8.processor.FileProcessor` class. We moved
+several helper functions into the :mod:`flake8.processor` module (see also
+:ref:`Processor Utility Functions <processor_utility_functions>`).
+
+
+API Reference
+-------------
+
+.. autoclass:: flake8.checker.FileChecker
+    :members:
+
+.. autoclass:: flake8.checker.Manager
+    :members:
+
+.. autoclass:: flake8.processor.FileProcessor
+    :members:
+
+
+.. _processor_utility_functions:
+
+Utility Functions
+`````````````````
+
+.. autofunction:: flake8.processor.count_parentheses
+
+.. autofunction:: flake8.processor.expand_indent
+
+.. autofunction:: flake8.processor.is_eol_token
+
+.. autofunction:: flake8.processor.is_multiline_string
+
+.. autofunction:: flake8.processor.log_token
+
+.. autofunction:: flake8.processor.mutate_string
+
+.. autofunction:: flake8.processor.token_is_comment
+
+.. autofunction:: flake8.processor.token_is_newline
+
+.. Substitutions
+.. |FileChecker| replace:: :class:`~flake8.checker.FileChecker`
+.. |Manager| replace:: :class:`~flake8.checker.Manager`

docs/source/internal/cli.rst

@@ -0,0 +1,26 @@
+Command Line Interface
+======================
+
+The command line interface of |Flake8| is modeled as an application via
+:class:`~flake8.main.cli.Application`. When a user runs ``flake8`` at their
+command line, :func:`~flake8.main.cli.main` is run which handles
+management of the application.
+
+User input is parsed *twice* to accomodate logging and verbosity options
+passed by the user as early as possible.
+This is so as much logging can be produced as possible.
+
+The default |Flake8| options are registered by
+:func:`~flake8.main.options.register_default_options`. Trying to register
+these options in plugins will result in errors.
+
+
+API Documentation
+-----------------
+
+.. autofunction:: flake8.main.cli.main
+
+.. autoclass:: flake8.main.application.Application
+    :members:
+
+.. autofunction:: flake8.main.options.register_default_options

docs/source/internal/contributing.rst

@@ -0,0 +1,202 @@
+========================
+ Contributing to Flake8
+========================
+
+There are many ways to contriubte to |Flake8|, and we encourage them all:
+
+- contributing bug reports and feature requests
+
+- contributing documenation (and yes that includes this document)
+
+- reviewing and triaging bugs and merge requests
+
+Before you go any further, please allow me to reassure you that I do want
+*your* contribution. If you think your contribution might not be valuable, I
+reassure you that any help you can provide *is* valuable.
+
+
+Code of Conduct
+===============
+
+|Flake8| adheres to the `Python Code Quality Authority's Code of Conduct`_.
+Any violations of the Code of Conduct should be reported to Ian Cordasco
+(graffatcolmingov [at] gmail [dot] com).
+
+
+Setting Up A Development Environment
+====================================
+
+To contribute to |Flake8|'s development, you simply need:
+
+- Python (one of the versions we support)
+
+- `tox`_
+
+  We suggest installing this like:
+
+  .. prompt:: bash
+
+        pip install --user tox
+
+  Or
+
+  .. prompt:: bash
+
+        python<version> -m pip install --user tox
+
+- your favorite editor
+
+
+Filing a Bug
+============
+
+When filing a bug against |Flake8|, please fill out the issue template as it
+is provided to you by `GitLab`_. If your bug is in reference to one of the
+checks that |Flake8| reports by default, please do not report them to |Flake8|
+unless |Flake8| is doing something to prevent the check from running or you
+have some reason to believe |Flake8| is inhibiting the effectiveness of the
+check.
+
+**Please search for closed and open bug reports before opening new ones.**
+
+All bug reports about checks should go to their respective projects:
+
+- Error codes starting with ``E`` and ``W`` should be reported to
+  `pycodestyle`_.
+
+- Error codes starting with ``F`` should be reported to `pyflakes`_
+
+- Error codes starting with ``C`` should be reported to `mccabe`_
+
+
+Requesting a New Feature
+========================
+
+When requesting a new feature in |Flake8|, please fill out the issue template.
+Please also note if there are any existing alternatives to your new feature
+either via plugins, or combining command-line options. Please provide example
+use cases. For example, do not ask for a feature like this:
+
+    I need feature frobulate for my job.
+
+Instead ask:
+
+    I need |Flake8| to frobulate these files because my team expects them to
+    frobulated but |Flake8| currently does not frobulate them. We tried using
+    ``--filename`` but we could not create a pattern that worked.
+
+The more you explain about *why* you need a feature, the more likely we are to
+understand your needs and help you to the best of our ability.
+
+
+Contributing Documentation
+==========================
+
+To contribute to |Flake8|'s documentation, you might want to first read a
+little about reStructuredText or Sphinx. |Flake8| has a :ref:`guide of best
+practices <docs-style>` when contributing to our documentation. For the most
+part, you should be fine following the structure and style of the rest of
+|Flake8|'s documentation.
+
+All of |Flake8|'s documentation is written in reStructuredText and rendered by
+Sphinx. The source (reStructuredText) lives in ``docs/source/``. To build
+the documentation the way our Continuous Integration does, run:
+
+.. prompt:: bash
+
+    tox -e docs
+
+To view the documentation locally, you can also run:
+
+.. prompt:: bash
+
+    tox -e serve-docs
+
+You can run the latter in a separate terminal and continuously re-run the
+documentation generation and refresh the documentation you're working on.
+
+.. note::
+
+    We lint our documentation just like we lint our code.
+    You should also run:
+
+    .. prompt:: bash
+
+        tox -e linters
+
+    After making changes and before pushing them to ensure that they will
+    pass our CI tests.
+
+
+Contributing Code
+=================
+
+|Flake8| development happens on `GitLab`_. Code contributions should be
+submitted there.
+
+Merge requests should:
+
+- Fix one issue and fix it well
+
+  Fix the issue, but do not include extraneous refactoring or code
+  reformatting. In other words, keep the diff short, but only as short
+  as is necessary to fix the bug appropriately and add sufficient testing
+  around it. Long diffs are fine, so long as everything that it includes
+  is necessary to the purpose of the merge request.
+
+- Have descriptive titles and descriptions
+
+  Searching old merge requests is made easier when a merge request is well
+  described.
+
+- Have commits that follow this style:
+
+  .. code::
+
+        Create a short title that is 50 characters long
+
+        Ensure the title and commit message use the imperative voice. The
+        commit and you are doing something. Also, please ensure that the
+        body of the commit message does not exceed 72 characters.
+
+        The body may have multiple paragraphs as necessary.
+
+        The final line of the body references the issue appropriately.
+
+
+Reviewing and Triaging Issues and Merge Requests
+================================================
+
+When reviewing other people's merge requests and issues, please be
+**especially** mindful of how the words you choose can be read by someone
+else. We strive for professional code reviews that do not insult the
+contributor's intelligence or impugn their character. The code review
+should be focused on the code, it's effectiveness, and whether it is
+appropriate for |Flake8|.
+
+If you have the ability to edit an issue or merge request's labels, please do
+so to make search and prioritization easier.
+
+|Flake8| uses milestones with both issues and merge requests. This provides
+direction for other contributors about when an issue or merge request will be
+delivered.
+
+
+.. links
+.. _Python Code Quality Authority's Code of Conduct:
+    http://meta.pycqa.org/en/latest/code-of-conduct.html
+
+.. _tox:
+    https://tox.readthedocs.io/
+
+.. _GitLab:
+    https://gitlab.com/pycqa/flake8
+
+.. _pycodestyle:
+    https://github.com/pycqa/pycodestyle
+
+.. _pyflakes:
+    https://github.com/pyflakes/pyflakes
+
+.. _mccabe:
+    https://github.com/pycqa/mccabe

docs/source/internal/formatters.rst

@@ -0,0 +1,47 @@
+=====================
+ Built-in Formatters
+=====================
+
+By default |Flake8| has two formatters built-in, ``default`` and ``pylint``.
+These correspond to two classes |DefaultFormatter| and |PylintFormatter|.
+
+In |Flake8| 2.0, pep8 handled formatting of errors and also allowed users to
+specify an arbitrary format string as a parameter to ``--format``. In order
+to allow for this backwards compatibility, |Flake8| 3.0 made two choices:
+
+#. To not limit a user's choices for ``--format`` to the format class names
+
+#. To make the default formatter attempt to use the string provided by the
+   user if it cannot find a formatter with that name.
+
+Default Formatter
+=================
+
+The |DefaultFormatter| continues to use the same default format string as
+pep8: ``'%(path)s:%(row)d:%(col)d: %(code)s %(text)s'``.
+
+To provide the default functionality it overrides two methods:
+
+#. ``after_init``
+
+#. ``format``
+
+The former allows us to inspect the value provided to ``--format`` by the
+user and alter our own format based on that value. The second simply uses
+that format string to format the error.
+
+.. autoclass:: flake8.formatting.default.Default
+    :members:
+
+Pylint Formatter
+================
+
+The |PylintFormatter| simply defines the default Pylint format string from
+pep8: ``'%(path)s:%(row)d: [%(code)s] %(text)s'``.
+
+.. autoclass:: flake8.formatting.default.Pylint
+    :members:
+
+
+.. |DefaultFormatter| replace:: :class:`~flake8.formatting.default.Default`
+.. |PylintFormatter| replace:: :class:`~flake8.formatting.default.Pylint`

docs/source/internal/index.rst

@@ -0,0 +1,26 @@
+==============================
+ Exploring Flake8's Internals
+==============================
+
+While writing |Flake8| 3.0, the developers attempted to capture some reasoning
+and decision information in internal documentation meant for future developers
+and maintaners. Most of this information is unnecessary for users and plugin
+developers. Some of it, however, is linked to from the plugin development
+documentation.
+
+Keep in mind that not everything will be here and you may need to help pull
+information out of the developers' heads and into these documents. Please
+pull gently.
+
+.. toctree::
+    :maxdepth: 2
+
+    contributing
+    writing-documentation
+    releases
+    checker
+    cli
+    formatters
+    option_handling
+    plugin_handling
+    utils

docs/source/internal/option_handling.rst

@@ -0,0 +1,234 @@
+Option and Configuration Handling
+=================================
+
+Option Management
+-----------------
+
+Command-line options are often also set in configuration files for |Flake8|.
+While not all options are meant to be parsed from configuration files, many
+default options are also parsed from configuration files as well as
+most plugin options.
+
+In |Flake8| 2, plugins received a :class:`optparse.OptionParser` instance and
+called :meth:`optparse.OptionParser.add_option` to register options. If the
+plugin author also wanted to have that option parsed from config files they
+also had to do something like:
+
+.. code-block:: python
+
+    parser.config_options.append('my_config_option')
+    parser.config_options.extend(['config_opt1', 'config_opt2'])
+
+This was previously undocumented and led to a lot of confusion about why
+registered options were not automatically parsed from configuration files.
+
+Since |Flake8| 3 was rewritten from scratch, we decided to take a different
+approach to configuration file parsing. Instead of needing to know about an
+undocumented attribute that pep8 looks for, |Flake8| 3 now accepts a parameter
+to ``add_option``, specifically ``parse_from_config`` which is a boolean
+value.
+
+|Flake8| does this by creating its own abstractions on top of :mod:`optparse`.
+The first abstraction is the :class:`flake8.options.manager.Option` class. The
+second is the :class:`flake8.options.manager.OptionManager`. In fact, we add
+three new parameters:
+
+- ``parse_from_config``
+
+- ``comma_separated_list``
+
+- ``normalize_paths``
+
+The last two are not specifically for configuration file handling, but they
+do improve that dramatically. We found that there were options that, when
+specified in a configuration file, often necessitated being spit
+multiple lines and those options were almost always comma-separated. For
+example, let's consider a user's list of ignored error codes for a project:
+
+.. code-block:: ini
+
+    [flake8]
+    ignore =
+        # Reasoning
+        E111,
+        # Reasoning
+        E711,
+        # Reasoning
+        E712,
+        # Reasoning
+        E121,
+        # Reasoning
+        E122,
+        # Reasoning
+        E123,
+        # Reasoning
+        E131,
+        # Reasoning
+        E251
+
+It makes sense here to allow users to specify the value this way, but, the
+standard libary's :class:`configparser.RawConfigParser` class does returns a
+string that looks like
+
+.. code-block:: python
+
+    "\nE111,  \nE711,  \nE712,  \nE121,  \nE122,  \nE123,  \nE131,  \nE251  "
+
+This means that a typical call to :meth:`str.split` with ``','`` will not be
+sufficient here. Telling |Flake8| that something is a comma-separated list
+(e.g., ``comma_separated_list=True``) will handle this for you. |Flake8| will
+return:
+
+.. code-block:: python
+
+    ["E111", "E711", "E712", "E121", "E122", "E123", "E131", "E251"]
+
+Next let's look at how users might like to specify their ``exclude`` list.
+Presently OpenStack's Nova project has this line in their `tox.ini`_:
+
+.. code-block:: ini
+
+    exclude = .venv,.git,.tox,dist,doc,*openstack/common/*,*lib/python*,*egg,build,tools/xenserver*,releasenotes
+
+We think we can all agree that this would be easier to read like this:
+
+.. code-block:: ini
+
+    exclude =
+        .venv,
+        .git,
+        .tox,
+        dist,
+        doc,
+        *openstack/common/*,
+        *lib/python*,
+        *egg,
+        build,
+        tools/xenserver*,
+        releasenotes
+
+In this case, since these are actually intended to be paths, we would specify
+both ``comma_separated_list=True`` and ``normalize_paths=True`` because we
+want the paths to be provided to us with some consistency (either all absolute
+paths or not).
+
+Now let's look at how this will actually be used. Most plugin developers
+will receive an instance of :class:`~flake8.options.manager.OptionManager` so
+to ease the transition we kept the same API as the
+:class:`optparse.OptionParser` object. The only difference is that
+:meth:`~flake8.options.manager.OptionManager.add_option` accepts the three
+extra arguments we highlighted above.
+
+.. _tox.ini:
+    https://github.com/openstack/nova/blob/3eb190c4cfc0eefddac6c2cc1b94a699fb1687f8/tox.ini#L155
+
+Configuration File Management
+-----------------------------
+
+In |Flake8| 2, configuration file discovery and management was handled by
+pep8.  In pep8's 1.6 release series, it drastically broke how discovery and
+merging worked (as a result of trying to improve it). To avoid a dependency
+breaking |Flake8| again in the future, we have created our own discovery and
+management.
+As part of managing this ourselves, we decided to change management/discovery
+for 3.0.0. We have done the following:
+
+- User files (files stored in a user's home directory or in the XDG directory
+  inside their home directory) are the first files read. For example, if the
+  user has a ``~/.flake8`` file, we will read that first.
+
+- Project files (files stored in the current directory) are read next and
+  merged on top of the user file. In other words, configuration in project
+  files takes precedence over configuration in user files.
+
+- **New in 3.0.0** The user can specify ``--append-config <path-to-file>``
+  repeatedly to include extra configuration files that should be read and
+  take precedence over user and project files.
+
+- **New in 3.0.0** The user can specify ``--config <path-to-file>`` to so this
+  file is the only configuration file used. This is a change from |Flake8| 2
+  where pep8 would simply merge this configuration file into the configuration
+  generated by user and project files (where this takes precedence).
+
+- **New in 3.0.0** The user can specify ``--isolated`` to disable
+  configuration via discovered configuration files.
+
+To facilitate the configuration file management, we've taken a different
+approach to discovery and management of files than pep8. In pep8 1.5, 1.6, and
+1.7 configuration discovery and management was centralized in `66 lines of
+very terse python`_ which was confusing and not very explicit. The terseness
+of this function (|Flake8|'s authors believe) caused the confusion and
+problems with pep8's 1.6 series. As such, |Flake8| has separated out
+discovery, management, and merging into a module to make reasoning about each
+of these pieces easier and more explicit (as well as easier to test).
+
+Configuration file discovery is managed by the
+:class:`~flake8.options.config.ConfigFileFinder` object. This object needs to
+know information about the program's name, any extra arguments passed to it,
+and any configuration files that should be appended to the list of discovered
+files. It provides methods for finding the files and similiar methods for
+parsing those fles. For example, it provides
+:meth:`~flake8.options.config.ConfigFileFinder.local_config_files` to find
+known local config files (and append the extra configuration files) and it
+also provides :meth:`~flake8.options.config.ConfigFileFinder.local_configs`
+to parse those configuration files.
+
+.. note:: ``local_config_files`` also filters out non-existent files.
+
+Configuration file merging and managemnt is controlled by the
+:class:`~flake8.options.config.MergedConfigParser`. This requires the instance
+of :class:`~flake8.options.manager.OptionManager` that the program is using,
+the list of appended config files, and the list of extra arguments. This
+object is currently the sole user of the
+:class:`~flake8.options.config.ConfigFileFinder` object. It appropriately
+initializes the object and uses it in each of
+
+- :meth:`~flake8.options.config.MergedConfigParser.parse_cli_config`
+- :meth:`~flake8.options.config.MergedConfigParser.parse_local_config`
+- :meth:`~flake8.options.config.MergedConfigParser.parse_user_config`
+
+Finally,
+:meth:`~flake8.options.config.MergedConfigParser.merge_user_and_local_config`
+takes the user and local configuration files that are parsed by
+:meth:`~flake8.options.config.MergedConfigParser.parse_local_config` and
+:meth:`~flake8.options.config.MergedConfigParser.parse_user_config`. The
+main usage of the ``MergedConfigParser`` is in
+:func:`~flake8.options.aggregator.aggregate_options`.
+
+Aggregating Configuration File and Command Line Arguments
+---------------------------------------------------------
+
+:func:`~flake8.options.aggregator.aggregate_options` accepts an instance of
+:class:`~flake8.options.maanger.OptionManager` and does the work to parse the
+command-line arguments passed by the user necessary for creating an instance
+of :class:`~flake8.options.config.MergedConfigParser`.
+
+After parsing the configuration file, we determine the default ignore list. We
+use the defaults from the OptionManager and update those with the parsed
+configuration files. Finally we parse the user-provided options one last time
+using the option defaults and configuration file values as defaults. The
+parser merges on the command-line specified arguments for us so we have our
+final, definitive, aggregated options.
+
+.. _66 lines of very terse python:
+    https://github.com/PyCQA/pep8/blob/b8088a2b6bc5b76bece174efad877f764529bc74/pep8.py#L1981..L2047
+
+API Documentation
+-----------------
+
+.. autofunction:: flake8.options.aggregator.aggregate_options
+
+.. autoclass:: flake8.options.manager.Option
+    :members: __init__, normalize, to_optparse
+
+.. autoclass:: flake8.options.manager.OptionManager
+    :members:
+    :special-members:
+
+.. autoclass:: flake8.options.config.ConfigFileFinder
+    :members:
+    :special-members:
+
+.. autoclass:: flake8.options.config.MergedConfigParser
+    :members:
+    :special-members:

docs/source/internal/plugin_handling.rst

@@ -0,0 +1,129 @@
+Plugin Handling
+===============
+
+Plugin Management
+-----------------
+
+|Flake8| 3.0 added support for two other plugins besides those which define
+new checks. It now supports:
+
+- extra checks
+
+- alternative report formatters
+
+- listeners to auto-correct violations of checks
+
+To facilitate this, |Flake8| needed a more mature way of managing plugins.
+Thus, we developed the |PluginManager| which accepts a namespace and will load
+the plugins for that namespace. A |PluginManager| creates and manages many
+|Plugin| instances.
+
+A |Plugin| lazily loads the underlying entry-point provided by setuptools.
+The entry-point will be loaded either by calling
+:meth:`~flake8.plugins.manager.Plugin.load_plugin` or accessing the ``plugin``
+attribute. We also use this abstraction to retrieve options that the plugin
+wishes to register and parse.
+
+The only public method the |PluginManager| provides is
+:meth:`~flake8.plugins.manager.PluginManager.map`. This will accept a function
+(or other callable) and call it with each plugin as the first parameter.
+
+We build atop the |PluginManager| with the |PTM|. It is expected that users of
+the |PTM| will subclass it and specify the ``namespace``, e.g.,
+
+.. code-block:: python
+
+    class ExamplePluginType(flake8.plugin.manager.PluginTypeManager):
+        namespace = 'example-plugins'
+
+This provides a few extra methods via the |PluginManager|'s ``map`` method.
+
+Finally, we create three classes of plugins:
+
+- :class:`~flake8.plugins.manager.Checkers`
+
+- :class:`~flake8.plugins.manager.Listeners`
+
+- :class:`~flake8.plugins.manager.ReportFormatters`
+
+These are used to interact with each of the types of plugins individually.
+
+.. note::
+
+    Our inspiration for our plugin handling comes from the author's extensive
+    experience with ``stevedore``.
+
+Notifying Listener Plugins
+--------------------------
+
+One of the interesting challenges with allowing plugins to be notified each
+time an error or warning is emitted by a checker is finding listeners quickly
+and efficiently. It makes sense to allow a listener to listen for a certain
+class of warnings or just a specific warning. Hence, we need to allow all
+plugins that listen to a specific warning or class to be notified. For
+example, someone might register a listener for ``E1`` and another for ``E111``
+if ``E111`` is triggered by the code, both listeners should be notified.
+If ``E112`` is returned, then only ``E1`` (and any other listeners) would be
+notified.
+
+To implement this goal, we needed an object to store listeners in that would
+allow for efficient look up - a Trie (or Prefix Tree). Given that none of the
+existing packages on PyPI allowed for storing data on each node of the trie,
+it was left up to write our own as :class:`~flake8.plugins._trie.Trie`. On
+top of that we layer our :class:`~flake8.plugins.notifier.Notifier` class.
+
+Now when |Flake8| receives an error or warning, we can easily call the
+:meth:`~flake8.plugins.notifier.Notifier.notify` method and let plugins act on
+that knowledge.
+
+Default Plugins
+---------------
+
+Finally, |Flake8| has always provided its own plugin shim for Pyflakes. As
+part of that we carry our own shim in-tree and now store that in
+:mod:`flake8.plugins.pyflakes`.
+
+|Flake8| also registers plugins for pep8. Each check in pep8 requires
+different parameters and it cannot easily be shimmed together like Pyflakes
+was. As such, plugins have a concept of a "group". If you look at our
+:file:`setup.py` you will see that we register pep8 checks roughly like so:
+
+.. code::
+
+    pep8.<check-name> = pep8:<check-name>
+
+We do this to identify that ``<check-name>>`` is part of a group. This also
+enables us to special-case how we handle reporting those checks. Instead of
+reporting each check in the ``--version`` output, we report ``pep8`` and check
+``pep8`` the module for a ``__version__`` attribute. We only report it once
+to avoid confusing users.
+
+API Documentation
+-----------------
+
+.. autoclass:: flake8.plugins.manager.PluginManager
+    :members:
+    :special-members: __init__, __contains__, __getitem__
+
+.. autoclass:: flake8.plugins.manager.Plugin
+    :members:
+    :special-members: __init__
+
+.. autoclass:: flake8.plugins.manager.PluginTypeManager
+    :members:
+
+.. autoclass:: flake8.plugins.manager.Checkers
+    :members:
+
+.. autoclass:: flake8.plugins.manager.Listeners
+    :members: build_notifier
+
+.. autoclass:: flake8.plugins.manager.ReportFormatters
+
+.. autoclass:: flake8.plugins.notifier.Notifier
+
+.. autoclass:: flake8.plugins._trie.Trie
+
+.. |PluginManager| replace:: :class:`~flake8.plugins.manager.PluginManager`
+.. |Plugin| replace:: :class:`~flake8.plugins.manager.Plugin`
+.. |PTM| replace:: :class:`~flake8.plugins.manager.PluginTypeManager`

docs/source/internal/releases.rst

@@ -0,0 +1,99 @@
+==================
+ Releasing Flake8
+==================
+
+There is not much that is hard to find about how |Flake8| is released.
+
+- We use **major** releases (e.g., 2.0.0, 3.0.0, etc.) for big, potentially
+  backwards incompatible, releases.
+
+- We use **minor** releases (e.g., 2.1.0, 2.2.0, 3.1.0, 3.2.0, etc.) for
+  releases that contain features and dependency version changes.
+
+- We use **patch** releases (e.g., 2.1.1, 2.1.2, 3.0.1, 3.0.10, etc.) for
+  releases that contain *only* bug fixes.
+
+In this sense we follow semantic versioning. But we follow it as more of a set
+of guidelines. We're also not perfect, so we may make mistakes, and that's
+fine.
+
+
+Major Releases
+==============
+
+Major releases are often associated with backwards incompatibility. |Flake8|
+hopes to avoid those, but will occasionally need them.
+
+Historically, |Flake8| has generated major releases for:
+
+- Unvendoring dependencies (2.0)
+
+- Large scale refactoring (2.0, 3.0)
+
+- Subtly breaking CLI changes (3.0)
+
+- Breaking changes to its plugin interface (3.0)
+
+Major releases can also contain:
+
+- Bug fixes (which may have backwards incompatible solutions)
+
+- New features
+
+- Dependency changes
+
+
+Minor Releases
+==============
+
+Minor releases often have new features in them, which we define roughly as:
+
+- New command-line flags
+
+- New behaviour that does not break backwards compatibility
+
+- New errors detected by dependencies, e.g., by raising the upper limit on
+  PyFlakes we introduce F405
+
+- Bug fixes
+
+
+Patch Releases
+==============
+
+Patch releases should only ever have bug fixes in them.
+
+We do not update dependency constraints in patch releases. If you do not
+install |Flake8| from PyPI, there is a chance that your packager is using
+different requirements. Some downstream redistributors have been known to
+force a new version of PyFlakes, pep8/PyCodestyle, or McCabe into place.
+Occasionally this will cause breakage when using |Flake8|. There is little
+we can do to help you in those cases.
+
+
+Process
+=======
+
+To prepare a release, we create a file in :file:`docs/source/releases/` named:
+``{{ release_number }}.rst`` (e.g., ``3.0.0.rst``). We note bug fixes,
+improvements, and dependency version changes as well as other items of note
+for users.
+
+Before releasing, the following tox test environments must pass:
+
+- Python 2.7 (a.k.a., ``tox -e py27``)
+
+- Python 3.4 (a.k.a., ``tox -e py34``)
+
+- Python 3.5 (a.k.a., ``tox -e py35``)
+
+- PyPy (a.k.a., ``tox -e pypy``)
+
+- Linters (a.k.a., ``tox -e linters``)
+
+We tag the most recent commit that passes those items and contains our release
+notes.
+
+Finally, we run ``tox -e release`` to build source distributions (e.g.,
+``flake8-3.0.0.tar.gz``), universal wheels, and upload them to PyPI with
+Twine.

docs/source/internal/utils.rst

@@ -0,0 +1,127 @@
+===================
+ Utility Functions
+===================
+
+|Flake8| has a few utility functions that it uses internally.
+
+.. warning::
+
+    As should be implied by where these are documented, these are all
+    **internal** utility functions. Their signatures and return types
+    may change between releases without notice.
+
+    Bugs reported about these **internal** functions will be closed
+    immediately.
+
+    If functions are needed by plugin developers, they may be requested
+    in the bug tracker and after careful consideration they *may* be added
+    to the *documented* stable API.
+
+.. autofunction:: flake8.utils.parse_comma_separated_list
+
+:func:`~flake8.utils.parse_comma_separated_list` takes either a string like
+
+.. code-block:: python
+
+    "E121,W123,F904"
+    "E121,\nW123,\nF804"
+    "E121,\n\tW123,\n\tF804"
+
+Or it will take a list of strings (potentially with whitespace) such as
+
+.. code-block:: python
+
+    ["   E121\n", "\t\nW123   ", "\n\tF904\n    "]
+
+And converts it to a list that looks as follows
+
+.. code-block:: python
+
+    ["E121", "W123", "F904"]
+
+This function helps normalize any kind of comma-separated input you or |Flake8|
+might receive. This is most helpful when taking advantage of |Flake8|'s
+additional parameters to :class:`~flake8.options.manager.Option`.
+
+.. autofunction:: flake8.utils.normalize_path
+
+This utility takes a string that represents a path and returns the absolute
+path if the string has a ``/`` in it. It also removes trailing ``/``\ s.
+
+.. autofunction:: flake8.utils.normalize_paths
+
+This function utilizes :func:`~flake8.utils.parse_comma_separated_list` and
+:func:`~flake8.utils.normalize_path` to normalize it's input to a list of
+strings that should be paths.
+
+.. autofunction:: flake8.utils.stdin_get_value
+
+This function retrieves and caches the value provided on ``sys.stdin``. This
+allows plugins to use this to retrieve ``stdin`` if necessary.
+
+.. autofunction:: flake8.utils.is_windows
+
+This provides a convenient and explicitly named function that checks if we are
+currently running on a Windows (or ``nt``) operating system.
+
+.. autofunction:: flake8.utils.can_run_multiprocessing_on_windows
+
+This provides a separate and distinct check from
+:func:`~flake8.utils.is_windows` that allows us to check if the version of
+Python we're using can actually use multiprocessing on Windows.
+
+.. autofunction:: flake8.utils.is_using_stdin
+
+Another helpful function that is named only to be explicit given it is a very
+trivial check, this checks if the user specified ``-`` in their arguments to
+|Flake8| to indicate we should read from stdin.
+
+.. autofunction:: flake8.utils.filenames_from
+
+When provided an argument to |Flake8|, we need to be able to traverse
+directories in a convenient manner. For example, if someone runs
+
+.. code::
+
+    $ flake8 flake8/
+
+Then they want us to check all of the files in the directory ``flake8/``. This
+function will handle that while also handling the case where they specify a
+file like:
+
+.. code::
+
+    $ flake8 flake8/__init__.py
+
+
+.. autofunction:: flake8.utils.fnmatch
+
+The standard library's :func:`fnmatch.fnmatch` is excellent at deciding if a
+filename matches a single pattern. In our use case, however, we typically have
+a list of patterns and want to know if the filename matches any of them. This
+function abstracts that logic away with a little extra logic.
+
+.. autofunction:: flake8.utils.parameters_for
+
+|Flake8| analyzes the parameters to plugins to determine what input they are
+expecting. Plugins may expect one of the following:
+
+- ``physical_line`` to receive the line as it appears in the file
+
+- ``logical_line`` to receive the logical line (not as it appears in the file)
+
+- ``tree`` to receive the abstract syntax tree (AST) for the file
+
+We also analyze the rest of the parameters to provide more detail to the
+plugin. This function will return the parameters in a consistent way across
+versions of Python and will handle both classes and functions that are used as
+plugins. Further, if the plugin is a class, it will strip the ``self``
+argument so we can check the parameters of the plugin consistently.
+
+.. autofunction:: flake8.utils.parse_unified_diff
+
+To handle usage of :option:`flake8 --diff`, |Flake8| needs to be able
+to parse the name of the files in the diff as well as the ranges indicated the
+sections that have been changed. This function either accepts the diff as an
+argument or reads the diff from standard-in. It then returns a dictionary with
+filenames as the keys and sets of line numbers as the value.

docs/source/internal/writing-documentation.rst

@@ -0,0 +1,183 @@
+.. _docs-style:
+
+==================================
+ Writing Documentation for Flake8
+==================================
+
+The maintainers of |Flake8| believe strongly in benefit of style guides.
+Hence, for all contributors who wish to work on our documentation, we've
+put together a loose set of guidelines and best practices when adding to
+our documentation.
+
+
+View the docs locally before submitting
+=======================================
+
+You can and should generate the docs locally before you submit a pull request
+with your changes. You can build the docs by running:
+
+.. prompt:: bash
+
+    tox -e docs
+
+From the directory containing the ``tox.ini`` file (which also contains the
+``docs/`` directory that this file lives in).
+
+.. note::
+
+    If the docs don't build locally, they will not build in our continuous
+    integration system. We will generally not merge any pull request that
+    fails continuous integration.
+
+
+Run the docs linter tests before submitting
+===========================================
+
+You should run the ``doc8`` linter job before you're ready to commit and fix
+any errors found.
+
+
+Capitalize Flake8 in prose
+==========================
+
+We believe that by capitalizing |Flake8| in prose, we can help reduce
+confusion between the command-line usage of ``flake8`` and the project.
+
+We also have defined a global replacement ``|Flake8|`` that should be used
+and will replace each instance with ``:program:`Flake8```.
+
+
+Use the prompt directive for command-line examples
+==================================================
+
+When documenting something on the command-line, use the ``.. prompt::``
+directive to make it easier for users to copy and paste into their terminal.
+
+Example:
+
+.. code-block:: restructuredtext
+
+    .. prompt:: bash
+
+        flake8 --select E123,W503 dir/
+        flake8 --ignore E24,W504 dir
+
+
+Wrap lines around 79 characters
+===============================
+
+We use a maximum line-length in our documentation that is similar to the
+default in |Flake8|. Please wrap lines at 79 characters (or less).
+
+
+Use two new-lines before new sections
+=====================================
+
+After the final paragraph of a section and before the next section title,
+use two new-lines to separate them. This makes reading the plain-text
+document a little nicer. Sphinx ignores these when rendering so they have
+no semantic meaning.
+
+Example:
+
+.. code-block:: restructuredtext
+
+    Section Header
+    ==============
+
+    Paragraph.
+
+
+    Next Section Header
+    ===================
+
+    Paragraph.
+
+
+Surround document titles with equal symbols
+===========================================
+
+To indicate the title of a document, we place an equal number of ``=`` symbols
+on the lines before and after the title. For example:
+
+.. code-block:: restructuredtext
+
+    ==================================
+     Writing Documentation for Flake8
+    ==================================
+
+Note also that we "center" the title by adding a leading space and having
+extra ``=`` symbols at the end of those lines.
+
+
+Use the option template for new options
+=======================================
+
+All of |Flake8|'s command-line options are documented in the User Guide. Each
+option is documented individually using the ``.. option::`` directive provided
+by Sphinx. At the top of the document, in a reStructuredText comment, is a
+template that should be copied and pasted into place when documening new
+options.
+
+.. note::
+
+    The ordering of the options page is the order that options are printed
+    in the output of:
+
+    .. prompt:: bash
+
+        flake8 --help
+
+    Please insert your option documentation according to that order.
+
+
+Use anchors for easy reference linking
+======================================
+
+Use link anchors to allow for other areas of the documentation to use the
+``:ref:`` role for intralinking documentation. Example:
+
+.. code-block:: restructuredtext
+
+    .. _use-anchors:
+
+    Use anchors for easy reference linking
+    ======================================
+
+.. code-block:: restructuredtext
+
+    Somewhere in this paragraph we will :ref:`reference anchors
+    <use-anchors>`.
+
+.. note::
+
+    You do not need to provide custom text for the ``:ref:`` if the title of
+    the section has a title that is sufficient.
+
+
+Keep your audience in mind
+==========================
+
+|Flake8|'s documentation has three distinct (but not separate) audiences:
+
+#. Users
+
+#. Plugin Developers
+
+#. Flake8 Developers and Contributors
+
+At the moment, you're one of the third group (because you're contributing
+or thinking of contributing).
+
+Consider that most Users aren't very interested in the internal working of
+|Flake8|. When writing for Users, focus on how to do something or the
+behaviour of a certain piece of configuration or invocation.
+
+Plugin developers will only care about the internals of |Flake8| as much as
+they will have to interact with that. Keep discussions of internal to the
+mininmum required.
+
+Finally, Flake8 Developers and Contributors need to know how everything fits
+together. We don't need detail about every line of code, but cogent
+explanations and design specifications will help future developers understand
+the Hows and Whys of |Flake8|'s internal design.

docs/source/plugin-development/cross-compatibility.rst

@@ -0,0 +1,150 @@
+====================================
+ Writing Plugins For Flake8 2 and 3
+====================================
+
+Plugins have existed for |Flake8| 2.x for a few years. There are a number of
+these on PyPI already. While it did not seem reasonable for |Flake8| to attempt
+to provide a backwards compatible shim for them, we did decide to try to
+document the easiest way to write a plugin that's compatible across both
+versions.
+
+.. note::
+
+    If your plugin does not register options, it *should* Just Work.
+
+The **only** breaking change in |Flake8| 3.0 is the fact that we no longer
+check the option parser for a list of strings to parse from a config file. On
+|Flake8| 2.x, to have an option parsed from the configuration files that
+|Flake8| finds and parses you would have to do something like:
+
+.. code-block:: python
+
+    parser.add_option('-X', '--example-flag', type='string',
+                      help='...')
+    parser.config_options.append('example-flag')
+
+For |Flake8| 3.0, we have added *three* arguments to the
+:meth:`~flake8.options.manager.OptionManager.add_option` method you will call
+on the parser you receive:
+
+- ``parse_from_config`` which expects ``True`` or ``False``
+
+  When ``True``, |Flake8| will parse the option from the config files |Flake8|
+  finds.
+
+- ``comma_separated_list`` which expects ``True`` or ``False``
+
+  When ``True``, |Flake8| will split the string intelligently and handle
+  extra whitespace. The parsed value will be a list.
+
+- ``normalize_paths`` which expects ``True`` or ``False``
+
+  When ``True``, |Flake8| will:
+
+  * remove trailing path separators (i.e., ``os.path.sep``)
+
+  * return the absolute path for values that have the separator in them
+
+All three of these options can be combined or used separately.
+
+
+Parsing Options from Configuration Files
+========================================
+
+The example from |Flake8| 2.x now looks like:
+
+.. code-block:: python
+
+    parser.add_option('-X', '--example-flag', type='string',
+                      parse_from_config=True,
+                      help='...')
+
+
+Parsing Comma-Separated Lists
+=============================
+
+Now let's imagine that the option we want to add is expecting a comma-separatd
+list of values from the user (e.g., ``--select E123,W503,F405``). |Flake8| 2.x
+often forced users to parse these lists themselves since pep8 special-cased
+certain flags and left others on their own. |Flake8| 3.0 adds
+``comma_separated_list`` so that the parsed option is already a list for
+plugin authors. When combined with ``parse_from_config`` this means that users
+can also do something like:
+
+.. code-block:: ini
+
+    example-flag =
+        first,
+        second,
+        third,
+        fourth,
+        fifth
+
+And |Flake8| will just return the list:
+
+.. code-block:: python
+
+    ["first", "second", "third", "fourth", "fifth"]
+
+
+Normalizing Values that Are Paths
+=================================
+
+Finally, let's imagine that our new option wants a path or list of paths. To
+ensure that these paths are semi-normalized (the way |Flake8| 2.x used to
+work) we need only pass ``normalize_paths=True``. If you have specified
+``comma_separated_list=True`` then this will parse the value as a list of
+paths that have been normalized. Otherwise, this will parse the value
+as a single path.
+
+
+Option Handling on Flake8 2 and 3
+=================================
+
+So, in conclusion, we can now write our plugin that relies on registering
+options with |Flake8| and have it work on |Flake8| 2.x and 3.x.
+
+.. code-block:: python
+
+    option_args = ('-X', '--example-flag')
+    option_kwargs = {
+        'type': 'string',
+        'parse_from_config': True,
+        'help': '...',
+    }
+    try:
+        # Flake8 3.x registration
+        parser.add_option(*option_args, **option_kwargs)
+    except TypeError:
+        # Flake8 2.x registration
+        parse_from_config = option_kwargs.pop('parse_from_config', False)
+        parser.add_option(*option_args, **option_kwargs)
+        if parse_from_config:
+            parser.config_options.append(option_args[-1].lstrip('-'))
+
+
+Or, you can write a tiny helper function:
+
+.. code-block:: python
+
+    def register_opt(parser, *args, **kwargs):
+        try:
+            # Flake8 3.x registration
+            parser.add_option(*args, **kwargs)
+        except TypeError:
+            # Flake8 2.x registration
+            parse_from_config = kwargs.pop('parse_from_config', False)
+            parser.add_option(*args, **kwargs)
+            if parse_from_config:
+                parser.config_options.append(args[-1].lstrip('-'))
+
+.. code-block:: python
+
+    @classmethod
+    def register_options(cls, parser):
+        register_opt(parser, '-X', '--example-flag', type='string',
+                     parse_from_config=True, help='...')
+
+The transition period is admittedly not fantastic, but we believe that this
+is a worthwhile change for plugin developers going forward. We also hope to
+help with the transition phase for as many plugins as we can manage.

docs/source/plugin-development/formatters.rst

@@ -0,0 +1,54 @@
+.. _formatting-plugins:
+
+===========================================
+ Developing a Formatting Plugin for Flake8
+===========================================
+
+|Flake8| allowed for custom formatting plugins in version
+3.0.0. Let's write a plugin together:
+
+.. code-block:: python
+
+    from flake8.formatting import base
+
+
+    class Example(base.BaseFormatter):
+        """Flake8's example formatter."""
+
+        pass
+
+We notice, as soon as we start, that we inherit from |Flake8|'s
+:class:`~flake8.formatting.base.BaseFormatter` class. If we follow the
+:ref:`instructions to register a plugin <register-a-plugin>` and try to use
+our example formatter, e.g., ``flake8 --format=example`` then
+|Flake8| will fail because we did not implement the ``format`` method.
+Let's do that next.
+
+.. code-block:: python
+
+    class Example(base.BaseFormatter):
+        """Flake8's example formatter."""
+
+        def format(self, error):
+            return 'Example formatter: {0!r}'.format(error)
+
+With that we're done. Obviously this isn't a very useful formatter, but it
+should highlight the simplicitly of creating a formatter with Flake8. If we
+wanted to instead create a formatter that aggregated the results and returned
+XML, JSON, or subunit we could also do that. |Flake8| interacts with the
+formatter in two ways:
+
+#. It creates the formatter and provides it the options parsed from the
+   configuration files and command-line
+
+#. It uses the instance of the formatter and calls ``handle`` with the error.
+
+By default :meth:`flake8.formatting.base.BaseFormatter.handle` simply calls
+the ``format`` method and then ``write``. Any extra handling you wish to do
+for formatting purposes should override the ``handle`` method.
+
+API Documentation
+=================
+
+.. autoclass:: flake8.formatting.base.BaseFormatter
+    :members:

docs/source/plugin-development/index.rst

@@ -0,0 +1,56 @@
+============================
+ Writing Plugins for Flake8
+============================
+
+Since |Flake8| 2.0, the |Flake8| tool has allowed for extensions and custom
+plugins. In |Flake8| 3.0, we're expanding that ability to customize and
+extend **and** we're attempting to thoroughly document it. Some of the
+documentation in this section may reference third-party documentation to
+reduce duplication and to point you, the developer, towards the authoritative
+documentation for those pieces.
+
+Getting Started
+===============
+
+To get started writing a |Flake8| :term:`plugin` you first need:
+
+- An idea for a plugin
+
+- An available package name on PyPI
+
+- One or more versions of Python installed
+
+- A text editor or IDE of some kind
+
+- An idea of what *kind* of plugin you want to build:
+
+  * Formatter
+
+  * Check
+
+Once you've gathered these things, you can get started.
+
+All plugins for |Flake8| must be registered via `entry points`_. In this
+section we cover:
+
+- How to register your plugin so |Flake8| can find it
+
+- How to make |Flake8| provide your check plugin with information (via
+  command-line flags, function/class parameters, etc.)
+
+- How to make a formatter plugin
+
+- How to write your check plugin so that it works with |Flake8| 2.x and 3.x
+
+.. toctree::
+    :caption: Plugin Developer Documentation
+    :maxdepth: 2
+
+    registering-plugins
+    plugin-parameters
+    formatters
+    cross-compatibility
+
+
+.. _entry points:
+    https://setuptools.readthedocs.io/en/latest/pkg_resources.html#entry-points

docs/source/plugin-development/plugin-parameters.rst

@@ -0,0 +1,163 @@
+.. _plugin-parameters:
+
+==========================================
+ Receiving Information For A Check Plugin
+==========================================
+
+Plugins to |Flake8| have a great deal of information that they can request
+from a :class:`~flake8.processor.FileProcessor` instance. Historically,
+|Flake8| has supported two types of plugins:
+
+#. classes that accept parsed abstract syntax trees (ASTs)
+
+#. functions that accept a range of arguments
+
+|Flake8| now does not distinguish between the two types of plugins. Any plugin
+can accept either an AST or a range of arguments. Further, any plugin that has
+certain callable attributes can also register options and receive parsed
+options.
+
+
+Indicating Desired Data
+=======================
+
+|Flake8| inspects the plugin's signature to determine what parameters it
+expects using :func:`flake8.utils.parameters_for`.
+:attr:`flake8.plugins.manager.Plugin.parameters` caches the values so that
+each plugin makes that fairly expensive call once per plugin. When processing
+a file, a plugin can ask for any of the following:
+
+- :attr:`~flake8.processor.FileProcessor.blank_before`
+- :attr:`~flake8.processor.FileProcessor.blank_lines`
+- :attr:`~flake8.processor.FileProcessor.checker_state`
+- :attr:`~flake8.processor.FileProcessor.indect_char`
+- :attr:`~flake8.processor.FileProcessor.indent_level`
+- :attr:`~flake8.processor.FileProcessor.line_number`
+- :attr:`~flake8.processor.FileProcessor.logical_line`
+- :attr:`~flake8.processor.FileProcessor.max_line_length`
+- :attr:`~flake8.processor.FileProcessor.multiline`
+- :attr:`~flake8.processor.FileProcessor.noqa`
+- :attr:`~flake8.processor.FileProcessor.previous_indent_level`
+- :attr:`~flake8.processor.FileProcessor.previous_logical`
+- :attr:`~flake8.processor.FileProcessor.tokens`
+- :attr:`~flake8.processor.FileProcessor.total_lines`
+- :attr:`~flake8.processor.FileProcessor.verbose`
+
+Alternatively, a plugin can accept ``tree`` and ``filename``.
+``tree`` will be a parsed abstract syntax tree that will be used by plugins
+like PyFlakes and McCabe.
+
+
+Registering Options
+===================
+
+Any plugin that has callable attributes ``provide_options`` and
+``register_options`` can parse option information and register new options.
+
+Your ``register_options`` function should expect to receive an instance of
+|OptionManager|. An |OptionManager| instance behaves very similarly to
+:class:`optparse.OptionParser`. It, however, uses the layer that |Flake8| has
+developed on top of :mod:`optparse` to also handle configuration file parsing.
+:meth:`~flake8.options.manager.OptionManager.add_option` creates an |Option|
+which accepts the same parameters as :mod:`optparse` as well as three extra
+boolean parameters:
+
+- ``parse_from_config``
+
+  The command-line option should also be parsed from config files discovered
+  by |Flake8|.
+
+  .. note::
+
+      This takes the place of appending strings to a list on the
+      :class:`optparse.OptionParser`.
+
+- ``comma_separated_list``
+
+  The value provided to this option is a comma-separated list. After parsing
+  the value, it should be further broken up into a list. This also allows us
+  to handle values like:
+
+  .. code::
+
+      E123,E124,
+      E125,
+        E126
+
+- ``normalize_paths``
+
+  The value provided to this option is a path. It should be normalized to be
+  an absolute path. This can be combined with ``comma_separated_list`` to
+  allow a comma-separated list of paths.
+
+Each of these options works individually or can be combined. Let's look at a
+couple examples from |Flake8|. In each example, we will have
+``option_manager`` which is an instance of |OptionManager|.
+
+.. code-block:: python
+
+    option_manager.add_option(
+        '--max-line-length', type='int', metavar='n',
+        default=defaults.MAX_LINE_LENGTH, parse_from_config=True,
+        help='Maximum allowed line length for the entirety of this run. '
+             '(Default: %default)',
+    )
+
+Here we are adding the ``--max-line-length`` command-line option which is
+always an integer and will be parsed from the configuration file. Since we
+provide a default, we take advantage of :mod:`optparse`\ 's willingness to
+display that in the help text with ``%default``.
+
+.. code-block:: python
+
+    option_manager.add_option(
+        '--select', metavar='errors', default='',
+        parse_from_config=True, comma_separated_list=True,
+        help='Comma-separated list of errors and warnings to enable.'
+             ' For example, ``--select=E4,E51,W234``. (Default: %default)',
+    )
+
+In adding the ``--select`` command-line option, we're also indicating to the
+|OptionManager| that we want the value parsed from the config files and parsed
+as a comma-separated list.
+
+.. code-block:: python
+
+    option_manager.add_option(
+        '--exclude', metavar='patterns', default=defaults.EXCLUDE,
+        comma_separated_list=True, parse_from_config=True,
+        normalize_paths=True,
+        help='Comma-separated list of files or directories to exclude.'
+             '(Default: %default)',
+    )
+
+Finally, we show an option that uses all three extra flags. Values from
+``--exclude`` will be parsed from the config, converted from a comma-separated
+list, and then each item will be normalized.
+
+For information about other parameters to
+:meth:`~flake8.options.manager.OptionManager.add_option` refer to the
+documentation of :mod:`optparse`.
+
+
+Accessing Parsed Options
+========================
+
+When a plugin has a callable ``provide_options`` attribute, |Flake8| will call
+it and attempt to provide the |OptionManager| instance, the parsed options
+which will be an instance of :class:`optparse.Values`, and the extra arguments
+that were not parsed by the |OptionManager|. If that fails, we will just pass
+the :class:`optparse.Values`. In other words, your ``provide_options``
+callable will have one of the following signatures:
+
+.. code-block:: python
+
+    def provide_options(option_manager, options, args):
+        pass
+    # or
+    def provide_options(options):
+        pass
+
+.. substitutions
+.. |OptionManager| replace:: :class:`~flake8.options.manager.OptionManager`
+.. |Option| replace:: :class:`~flake8.options.manager.Option`

docs/source/plugin-development/registering-plugins.rst

@@ -0,0 +1,115 @@
+.. _register-a-plugin:
+
+==================================
+ Registering a Plugin with Flake8
+==================================
+
+To register any kind of plugin with |Flake8|, you need:
+
+#. A way to install the plugin (whether it is packaged on its own or
+   as part of something else). In this section, we will use a ``setup.py``
+   written for an example plugin.
+
+#. A name for your plugin that will (ideally) be unique.
+
+#. A somewhat recent version of setuptools (newer than 0.7.0 but preferably as
+   recent as you can attain).
+
+|Flake8| relies on functionality provided by setuptools called
+`Entry Points`_. These allow any package to register a plugin with |Flake8|
+via that package's ``setup.py`` file.
+
+Let's presume that we already have our plugin written and it's in a module
+called ``flake8_example``. We might have a ``setup.py`` that looks something
+like:
+
+.. code-block:: python
+
+    from __future__ import with_statement
+    import setuptools
+
+    requires = [
+        "flake8 > 3.0.0",
+    ]
+
+    flake8_entry_point = # ...
+
+    setuptools.setup(
+        name="flake8_example",
+        license="MIT",
+        version="0.1.0",
+        description="our extension to flake8",
+        author="Me",
+        author_email="example@example.com",
+        url="https://gitlab.com/me/flake8_example",
+        packages=[
+            "flake8_example",
+        ],
+        install_requires=requires,
+        entry_points={
+            flake8_entry_point: [
+                'X = flake8_example:ExamplePlugin',
+            ],
+        },
+        classifiers=[
+            "Environment :: Console",
+            "Intended Audience :: Developers",
+            "License :: OSI Approved :: MIT License",
+            "Programming Language :: Python",
+            "Programming Language :: Python :: 2",
+            "Programming Language :: Python :: 3",
+            "Topic :: Software Development :: Libraries :: Python Modules",
+            "Topic :: Software Development :: Quality Assurance",
+        ],
+    )
+
+Note specifically these lines:
+
+.. code-block:: python
+
+    flake8_entry_point = # ...
+
+    setuptools.setup(
+        # snip ...
+        entry_points={
+            flake8_entry_point: [
+                'X = flake8_example:ExamplePlugin',
+            ],
+        },
+        # snip ...
+    )
+
+We tell setuptools to register our entry point "X" inside the specific
+grouping of entry-points that flake8 should look in.
+
+|Flake8| presently looks at three groups:
+
+- ``flake8.extension``
+
+- ``flake8.listen``
+
+- ``flake8.report``
+
+If your plugin is one that adds checks to |Flake8|, you will use
+``flake8.extension``. If your plugin automatically fixes errors in code, you
+will use ``flake8.listen``.  Finally, if your plugin performs extra report
+handling (formatting, filtering, etc.) it will use ``flake8.report``.
+
+If our ``ExamplePlugin`` is something that adds checks, our code would look
+like:
+
+.. code-block:: python
+
+    setuptools.setup(
+        # snip ...
+        entry_points={
+            'flake8.extension': [
+                'X = flake8_example:ExamplePlugin',
+            ],
+        },
+        # snip ...
+    )
+
+
+.. _Entry Points:
+    https://pythonhosted.org/setuptools/pkg_resources.html#entry-points

docs/source/release-notes/0.6.0.rst

@@ -0,0 +1,4 @@
+0.6 - 2010-02-15
+----------------
+
+- Fix the McCabe metric on some loops

docs/source/release-notes/0.7.0.rst

@@ -0,0 +1,6 @@
+0.7 - 2010-02-18
+----------------
+
+- Fix pep8 initialization when run through Hg
+- Make pep8 short options work when run through the command line
+- Skip duplicates when controlling files via Hg

docs/source/release-notes/0.8.0.rst

@@ -0,0 +1,5 @@
+0.8 - 2011-02-27
+----------------
+
+- fixed hg hook
+- discard unexisting files on hook check

docs/source/release-notes/0.9.0.rst

@@ -0,0 +1,5 @@
+0.9 - 2011-11-09
+----------------
+
+- update pep8 version to 0.6.1
+- mccabe check: gracefully handle compile failure

docs/source/release-notes/1.0.0.rst

@@ -0,0 +1,5 @@
+1.0 - 2011-11-29
+----------------
+
+- Deactivates by default the complexity checker
+- Introduces the complexity option in the HG hook and the command line.

docs/source/release-notes/1.1.0.rst

@@ -0,0 +1,8 @@
+1.1 - 2012-02-14
+----------------
+
+- fixed the value returned by --version
+- allow the flake8: header to be more generic
+- fixed the "hg hook raises 'physical lines'" bug
+- allow three argument form of raise
+- now uses setuptools if available, for 'develop' command

docs/source/release-notes/1.2.0.rst

@@ -0,0 +1,6 @@
+1.2 - 2012-02-12
+----------------
+
+- added a git hook
+- now Python 3 compatible
+- mccabe and pyflakes have warning codes like pep8 now

docs/source/release-notes/1.3.0.rst

@@ -0,0 +1,4 @@
+1.3 - 2012-03-12
+----------------
+
+- fixed false W402 warning on exception blocks.

docs/source/release-notes/1.3.1.rst

@@ -0,0 +1,4 @@
+1.3.1 - 2012-05-19
+------------------
+
+- fixed support for Python 2.5

docs/source/release-notes/1.4.0.rst

@@ -0,0 +1,5 @@
+1.4 - 2012-07-12
+----------------
+
+- git_hook: Only check staged changes for compliance
+- use pep8 1.2

docs/source/release-notes/1.5.0.rst

@@ -0,0 +1,9 @@
+1.5 - 2012-10-13
+----------------
+
+- fixed the stdin
+- make sure mccabe catches the syntax errors as warnings
+- pep8 upgrade
+- added max_line_length default value
+- added Flake8Command and entry points if setuptools is around
+- using the setuptools console wrapper when available

docs/source/release-notes/1.6.0.rst

@@ -0,0 +1,14 @@
+1.6 - 2012-11-16
+----------------
+
+- changed the signatures of the ``check_file`` function in flake8/run.py,
+  ``skip_warning`` in flake8/util.py and the ``check``, ``checkPath``
+  functions in flake8/pyflakes.py.
+- fix ``--exclude`` and ``--ignore`` command flags (#14, #19)
+- fix the git hook that wasn't catching files not already added to the index
+  (#29)
+- pre-emptively includes the addition to pep8 to ignore certain lines.
+  Add ``# nopep8`` to the end of a line to ignore it. (#37)
+- ``check_file`` can now be used without any special prior setup (#21)
+- unpacking exceptions will no longer cause an exception (#20)
+- fixed crash on non-existent file (#38)

docs/source/release-notes/1.6.1.rst

@@ -0,0 +1,7 @@
+1.6.1 - 2012-11-24
+------------------
+
+- fixed the mercurial hook, a change from a previous patch was not properly
+  applied
+- fixed an assumption about warnings/error messages that caused an exception
+  to be thrown when McCabe is used

docs/source/release-notes/1.6.2.rst

@@ -0,0 +1,4 @@
+1.6.2 - 2012-11-25
+------------------
+
+- fixed the NameError: global name 'message' is not defined (#46)

docs/source/release-notes/1.7.0.rst

@@ -0,0 +1,9 @@
+1.7.0 - 2012-12-21
+------------------
+
+- Fixes part of #35: Exception for no WITHITEM being an attribute of Checker
+  for Python 3.3
+- Support stdin
+- Incorporate @phd's builtins pull request
+- Fix the git hook
+- Update pep8.py to the latest version

docs/source/release-notes/2.0.0.rst

@@ -0,0 +1,13 @@
+2.0.0 - 2013-02-23
+------------------
+
+- Pyflakes errors are prefixed by an ``F`` instead of an ``E``
+- McCabe complexity warnings are prefixed by a ``C`` instead of a ``W``
+- Flake8 supports extensions through entry points
+- Due to the above support, we **require** setuptools
+- We publish the `documentation <https://flake8.readthedocs.org/>`_
+- Fixes #13: pep8, pyflakes and mccabe become external dependencies
+- Split run.py into main.py, engine.py and hooks.py for better logic
+- Expose our parser for our users
+- New feature: Install git and hg hooks automagically
+- By relying on pyflakes (0.6.1), we also fixed #45 and #35

docs/source/release-notes/2.1.0.rst

@@ -0,0 +1,12 @@
+2.1.0 - 2013-10-26
+------------------
+
+- Add FLAKE8_LAZY and FLAKE8_IGNORE environment variable support to git and
+  mercurial hooks
+- Force git and mercurial hooks to repsect configuration in setup.cfg
+- Only check staged files if that is specified
+- Fix hook file permissions
+- Fix the git hook on python 3
+- Ignore non-python files when running the git hook
+- Ignore .tox directories by default
+- Flake8 now reports the column number for PyFlakes messages

docs/source/release-notes/2.2.0.rst

@@ -0,0 +1,12 @@
+2.2.0 - 2014-06-22
+------------------
+
+- New option ``doctests`` to run Pyflakes checks on doctests too
+- New option ``jobs`` to launch multiple jobs in parallel
+- Turn on using multiple jobs by default using the CPU count
+- Add support for ``python -m flake8`` on Python 2.7 and Python 3
+- Fix Git and Mercurial hooks: issues #88, #133, #148 and #149
+- Fix crashes with Python 3.4 by upgrading dependencies
+- Fix traceback when running tests with Python 2.6
+- Fix the setuptools command ``python setup.py flake8`` to read
+  the project configuration

docs/source/release-notes/2.2.1.rst

@@ -0,0 +1,5 @@
+2.2.1 - 2014-06-30
+------------------
+
+- Turn off multiple jobs by default. To enable automatic use of all CPUs, use
+  ``--jobs=auto``. Fixes #155 and #154.

docs/source/release-notes/2.2.2.rst

@@ -0,0 +1,5 @@
+2.2.2 - 2014-07-04
+------------------
+
+- Re-enable multiprocessing by default while fixing the issue Windows users
+  were seeing.

docs/source/release-notes/2.2.3.rst

@@ -0,0 +1,4 @@
+2.2.3 - 2014-08-25
+------------------
+
+- Actually turn multiprocessing on by default

docs/source/release-notes/2.2.4.rst

@@ -0,0 +1,20 @@
+2.2.4 - 2014-10-09
+------------------
+
+- Fix bugs triggered by turning multiprocessing on by default (again)
+
+  Multiprocessing is forcibly disabled in the following cases:
+
+  - Passing something in via stdin
+
+  - Analyzing a diff
+
+  - Using windows
+
+- Fix --install-hook when there are no config files present for pep8 or
+  flake8.
+
+- Fix how the setuptools command parses excludes in config files
+
+- Fix how the git hook determines which files to analyze (Thanks Chris
+  Buccella!)

docs/source/release-notes/2.2.5.rst

@@ -0,0 +1,6 @@
+2.2.5 - 2014-10-19
+------------------
+
+- Flush standard out when using multiprocessing
+
+- Make the check for "# flake8: noqa" more strict

docs/source/release-notes/2.3.0.rst

@@ -0,0 +1,10 @@
+2.3.0 - 2015-01-04
+------------------
+
+- **Feature**: Add ``--output-file`` option to specify a file to write to
+  instead of ``stdout``.
+
+- **Bug** Fix interleaving of output while using multiprocessing
+  (`GitLab#17`_)
+
+.. _GitLab#17: https://gitlab.com/pycqa/flake8/issues/17

docs/source/release-notes/2.4.0.rst

@@ -0,0 +1,33 @@
+2.4.0 - 2015-03-07
+------------------
+
+- **Bug** Print filenames when using multiprocessing and ``-q`` option.
+  (`GitLab#31`_)
+
+- **Bug** Put upper cap on dependencies. The caps for 2.4.0 are:
+
+  - ``pep8 < 1.6`` (Related to `GitLab#35`_)
+
+  - ``mccabe < 0.4``
+
+  - ``pyflakes < 0.9``
+
+  See also `GitLab#32`_
+
+- **Bug** Files excluded in a config file were not being excluded when flake8
+  was run from a git hook. (`GitHub#2`_)
+
+- **Improvement** Print warnings for users who are providing mutually
+  exclusive options to flake8. (`GitLab#8`_, `GitLab!18`_)
+
+- **Feature** Allow git hook configuration to live in ``.git/config``.
+  See the updated `VCS hooks docs`_ for more details. (`GitLab!20`_)
+
+.. _GitHub#2: https://github.com/pycqa/flake8/pull/2
+.. _GitLab#8: https://gitlab.com/pycqa/flake8/issues/8
+.. _GitLab#31: https://gitlab.com/pycqa/flake8/issues/31
+.. _GitLab#32: https://gitlab.com/pycqa/flake8/issues/32
+.. _GitLab#35: https://gitlab.com/pycqa/flake8/issues/35
+.. _GitLab!18: https://gitlab.com/pycqa/flake8/merge_requests/18
+.. _GitLab!20: https://gitlab.com/pycqa/flake8/merge_requests/20
+.. _VCS hooks docs: https://flake8.readthedocs.org/en/latest/vcs.html

docs/source/release-notes/2.4.1.rst

@@ -0,0 +1,12 @@
+2.4.1 - 2015-05-18
+------------------
+
+- **Bug** Do not raise a ``SystemError`` unless there were errors in the
+  setuptools command. (`GitLab#39`_, `GitLab!23`_)
+
+- **Bug** Do not verify dependencies of extensions loaded via entry-points.
+
+- **Improvement** Blacklist versions of pep8 we know are broken
+
+.. _GitLab#39: https://gitlab.com/pycqa/flake8/issues/39
+.. _GitLab!23: https://gitlab.com/pycqa/flake8/merge_requests/23

docs/source/release-notes/2.5.0.rst

@@ -0,0 +1,25 @@
+2.5.0 - 2015-10-26
+------------------
+
+- **Improvement** Raise cap on PyFlakes for Python 3.5 support
+
+- **Improvement** Avoid deprecation warnings when loading extensions
+  (`GitLab#59`_, `GitLab#90`_)
+
+- **Improvement** Separate logic to enable "off-by-default" extensions
+  (`GitLab#67`_)
+
+- **Bug** Properly parse options to setuptools Flake8 command (`GitLab!41`_)
+
+- **Bug** Fix exceptions when output on stdout is truncated before Flake8
+  finishes writing the output (`GitLab#69`_)
+
+- **Bug** Fix error on OS X where Flake8 can no longer acquire or create new
+  semaphores (`GitLab#74`_)
+
+.. _GitLab!41: https://gitlab.com/pycqa/flake8/merge_requests/41
+.. _GitLab#59: https://gitlab.com/pycqa/flake8/issues/59
+.. _GitLab#67: https://gitlab.com/pycqa/flake8/issues/67
+.. _GitLab#69: https://gitlab.com/pycqa/flake8/issues/69
+.. _GitLab#74: https://gitlab.com/pycqa/flake8/issues/74
+.. _GitLab#90: https://gitlab.com/pycqa/flake8/issues/90

docs/source/release-notes/2.5.1.rst

@@ -0,0 +1,13 @@
+2.5.1 - 2015-12-08
+------------------
+
+- **Bug** Properly look for ``.flake8`` in current working directory
+  (`GitLab#103`_)
+
+- **Bug** Monkey-patch ``pep8.stdin_get_value`` to cache the actual value in
+  stdin. This helps plugins relying on the function when run with
+  multiprocessing. (`GitLab#105`_, `GitLab#107`_)
+
+.. _GitLab#103: https://gitlab.com/pycqa/flake8/issues/103
+.. _GitLab#105: https://gitlab.com/pycqa/flake8/issues/105
+.. _GitLab#107: https://gitlab.com/pycqa/flake8/issues/107

docs/source/release-notes/2.5.2.rst

@@ -0,0 +1,7 @@
+2.5.2 - 2016-01-30
+------------------
+
+- **Bug** Parse ``output_file`` and ``enable_extensions`` from config files
+
+- **Improvement** Raise upper bound on mccabe plugin to allow for version
+  0.4.0

docs/source/release-notes/2.5.3.rst

@@ -0,0 +1,5 @@
+2.5.3 - 2016-02-11
+------------------
+
+- **Bug** Actually parse ``output_file`` and ``enable_extensions`` from config
+  files

docs/source/release-notes/2.5.4.rst

@@ -0,0 +1,4 @@
+2.5.4 - 2016-02-11
+------------------
+
+- **Bug** Missed an attribute rename during the v2.5.3 release.

docs/source/release-notes/2.5.5.rst

@@ -0,0 +1,7 @@
+2.5.5 - 2016-06-14
+------------------
+
+- **Bug** Fix setuptools integration when parsing config files
+
+- **Bug** Don't pass the user's config path as the config_file when creating a
+  StyleGuide

docs/source/release-notes/2.6.1.rst

@@ -0,0 +1,6 @@
+2.6.1 - 2016-06-25
+------------------
+
+- **Bug** Update the config files to search for to include ``setup.cfg`` and
+  ``tox.ini``. This was broken in 2.5.5 when we stopped passing
+  ``config_file`` to our Style Guide

docs/source/release-notes/3.0.0.rst

@@ -0,0 +1,42 @@
+3.0.0b1 -- 2016-06-25
+---------------------
+
+- Rewrite our documentation from scratch! (http://flake8.pycqa.org)
+
+- Drop explicit support for Pythons 2.6, 3.2, and 3.3.
+
+- Remove dependence on pep8/pycodestyle for file processing, plugin
+  dispatching, and more. We now control all of this while keeping backwards
+  compatibility.
+
+- ``--select`` and ``--ignore`` can now both be specified and try to find the
+  most specific rule from each. For example, if you do ``--select E --ignore
+  E123`` then we will report everything that starts with ``E`` except for
+  ``E123``. Previously, you would have had to do ``--ignore E123,F,W`` which
+  will also still work, but the former should be far more intuitive.
+
+- Add support for in-line ``# noqa`` comments to specify **only** the error
+  codes to be ignored, e.g., ``# noqa: E123,W503``
+
+- Add entry-point for formatters as well as a base class that new formatters
+  can inherit from. See the documentation for more details.
+
+- Add detailed verbose output using the standard library logging module.
+
+- Enhance our usage of optparse for plugin developers by adding new parameters
+  to the ``add_option`` that plugins use to register new options.
+
+- Update ``--install-hook`` to require the name of version control system hook
+  you wish to install a Flake8.
+
+- Stop checking sub-directories more than once via the setuptools command
+
+- When passing a file on standard-in, allow the caller to specify
+  ``--stdin-display-name`` so the output is properly formatted
+
+- The Git hook now uses ``sys.executable`` to format the shebang line.
+  This allows Flake8 to install a hook script from a virtualenv that points to
+  that virtualenv's Flake8 as opposed to a global one (without the virtualenv
+  being sourced).
+
+- When using ``--count``, the output is no longer written to stderr.

docs/source/release-notes/index.rst

@@ -0,0 +1,41 @@
+===========================
+ Release Notes and History
+===========================
+
+All of the release notes that have been recorded for Flake8 are organized here
+with the newest releases first.
+
+.. toctree::
+    3.0.0
+    2.5.5
+    2.5.4
+    2.5.3
+    2.5.2
+    2.5.1
+    2.5.0
+    2.4.1
+    2.4.0
+    2.3.0
+    2.2.5
+    2.2.4
+    2.2.3
+    2.2.2
+    2.2.1
+    2.2.0
+    2.1.0
+    2.0.0
+    1.7.0
+    1.6.2
+    1.6.1
+    1.6.0
+    1.5.0
+    1.4.0
+    1.3.1
+    1.3.0
+    1.2.0
+    1.1.0
+    1.0.0
+    0.9.0
+    0.8.0
+    0.7.0
+    0.6.0

docs/source/requirements.txt

@@ -0,0 +1,4 @@
+sphinx>=1.3.0
+sphinx_rtd_theme
+sphinx-prompt
+configparser

docs/source/user/configuration.rst

@@ -0,0 +1,227 @@
+.. _configuration:
+
+====================
+ Configuring Flake8
+====================
+
+Once you have learned how to :ref:`invoke <invocation>` |Flake8|, you will soon
+want to learn how to configure it so you do not have to specify the same
+options every time you use it.
+
+This section will show you how to make
+
+.. prompt:: bash
+
+    flake8
+
+Remember that you want to specify certain options without writing
+
+.. prompt:: bash
+
+    flake8 --select E123,W456 --enable-extensions H111
+
+
+Configuration Locations
+=======================
+
+|Flake8| supports storing its configuration in the following places:
+
+- Your top-level user directory
+
+- In your project in one of ``setup.cfg``, ``tox.ini``, or ``.flake8``.
+
+
+"User" Configuration
+--------------------
+
+|Flake8| allows a user to use "global" configuration file to store preferences.
+The user configuration file is expected to be stored somewhere in the user's
+"home" directory.
+
+- On Windows the "home" directory will be something like
+  ``C:\\Users\sigmavirus24``, a.k.a, ``~\``.
+
+- On Linux and other Unix like systems (including OS X) we will look in
+  ``~/``.
+
+Note that |Flake8| looks for ``~\.flake8`` on Windows and ``~/.config/flake8``
+on Linux and other Unix systems.
+
+User configuration files use the same syntax as Project Configuration files.
+Keep reading to see that syntax.
+
+
+Project Configuration
+---------------------
+
+|Flake8| is written with the understanding that people organize projects into
+sub-directories. Let's take for example |Flake8|'s own project structure
+
+.. code::
+
+    flake8
+    ├── docs
+    │   ├── build
+    │   └── source
+    │       ├── _static
+    │       ├── _templates
+    │       ├── dev
+    │       ├── internal
+    │       └── user
+    ├── flake8
+    │   ├── formatting
+    │   ├── main
+    │   ├── options
+    │   └── plugins
+    └── tests
+        ├── fixtures
+        │   └── config_files
+        ├── integration
+        └── unit
+
+In the top-level ``flake8`` directory (which contains ``docs``, ``flake8``,
+and ``tests``) there's also ``tox.ini`` and ``setup.cfg`` files. In our case,
+we keep our |Flake8| configuration in ``tox.ini``. Regardless of whether you
+keep your config in ``.flake8``, ``setup.cfg``, or ``tox.ini`` we expect you
+to use INI to configure |Flake8| (since each of these files already uses INI
+as a format). This means that any |Flake8| configuration you wish to set needs
+to be in the ``flake8`` section, which means it needs to start like so:
+
+.. code-block:: ini
+
+    [flake8]
+
+Each command-line option that you want to specify in your config file can
+be named in either of two ways:
+
+#. Using underscores (``_``) instead of hyphens (``-``)
+
+#. Simply using hyphens (without the leading hyphens)
+
+.. note::
+
+    Not every |Flake8| command-line option can be specified in the
+    configuration file. See :ref:`our list of options <options-list>` to
+    determine which options will be parsed from the configuration files.
+
+Let's actually look at |Flake8|'s own configuration section:
+
+.. code-block:: ini
+
+    [flake8]
+    ignore = D203
+    exclude = .git,__pycache__,docs/source/conf.py,old,build,dist
+    max-complexity = 10
+
+This is equivalent to:
+
+.. prompt:: bash
+
+    flake8 --ignore D203 \
+             --exclude .git,__pycache__,docs/source/conf.py,old,build,dist \
+             --max-complexity 10
+
+In our case, if we wanted to, we could also do
+
+.. code-block:: ini
+
+    [flake8]
+    ignore = D203
+    exclude =
+        .git,
+        __pycache__,
+        docs/source/conf.py,
+        old,
+        build,
+        dist
+    max-complexity = 10
+
+This would allow us to add comments for why we're excluding items, e.g.,
+
+.. code-block:: ini
+
+    [flake8]
+    ignore = D203
+    exclude =
+        # No need to traverse our git directory
+        .git,
+        # There's no value in checking cache directories
+        __pycache__,
+        # The conf file is mostly autogenerated, ignore it
+        docs/source/conf.py,
+        # The old directory contains Flake8 2.0
+        old,
+        # This contains our built documentation
+        build,
+        # This contains builds of flake8 that we don't want to check
+        dist
+    max-complexity = 10
+
+.. note::
+
+    If you're using Python 2, you will notice that we download the
+    :mod:`configparser` backport from PyPI. That backport enables us to
+    support this behaviour on all supported versions of Python.
+
+    Please do **not** open issues about this dependency to |Flake8|.
+
+.. note::
+
+    You can also specify ``--max-complexity`` as ``max_complexity = 10``.
+
+This is also useful if you have a long list of error codes to ignore. Let's
+look at a portion of OpenStack's Swift `project configuration`_:
+
+.. code-block:: ini
+
+    [flake8]
+    # it's not a bug that we aren't using all of hacking, ignore:
+    # F812: list comprehension redefines ...
+    # H101: Use TODO(NAME)
+    # H202: assertRaises Exception too broad
+    # H233: Python 3.x incompatible use of print operator
+    # H301: one import per line
+    # H306: imports not in alphabetical order (time, os)
+    # H401: docstring should not start with a space
+    # H403: multi line docstrings should end on a new line
+    # H404: multi line docstring should start without a leading new line
+    # H405: multi line docstring summary not separated with an empty line
+    # H501: Do not use self.__dict__ for string formatting
+    ignore = F812,H101,H202,H233,H301,H306,H401,H403,H404,H405,H501
+
+They use the comments to describe the check but they could also write this as:
+
+.. code-block:: ini
+
+    [flake8]
+    # it's not a bug that we aren't using all of hacking
+    ignore =
+        # F812: list comprehension redefines ...
+        F812,
+        # H101: Use TODO(NAME)
+        H101,
+        # H202: assertRaises Exception too broad
+        H202,
+        # H233: Python 3.x incompatible use of print operator
+        H233,
+        # H301: one import per line
+        H301,
+        # H306: imports not in alphabetical order (time, os)
+        H306,
+        # H401: docstring should not start with a space
+        H401,
+        # H403: multi line docstrings should end on a new line
+        H403,
+        # H404: multi line docstring should start without a leading new line
+        H404,
+        # H405: multi line docstring summary not separated with an empty line
+        H405,
+        # H501: Do not use self.__dict__ for string formatting
+        H501
+
+Or they could use each comment to describe **why** they've ignored the check.
+|Flake8| knows how to parse these lists and will appropriatey handle
+these situations.
+
+.. _project configuration:
+    https://github.com/openstack/swift/blob/3944d820387f08372c1a29444f4af7d8e6090ae9/tox.ini#L66..L81

docs/source/user/ignoring-errors.rst

@@ -0,0 +1,90 @@
+=============================
+ Ignoring Errors with Flake8
+=============================
+
+By default, |Flake8| has a list of error codes that it ignores. The list used
+by a version of |Flake8| may be different than the list used by a different
+version. To see the default list, :option:`flake8 --help` will
+show the output with the current default list.
+
+
+Changing the Ignore List
+========================
+
+If we want to change the list of ignored codes for a single run, we can use
+:option:`flake8 --ignore` to specify a comma-separated list of codes for a
+specific run on the command-line, e.g.,
+
+.. prompt:: bash
+
+    flake8 --ignore=E1,E23,W503 path/to/files/ path/to/more/files/
+
+This tells |Flake8| to ignore any error codes starting with ``E1``, ``E23``,
+or ``W503`` while it is running.
+
+.. note::
+
+    The documentation for :option:`flake8 --ignore` shows examples for how
+    to change the ignore list in the configuration file. See also
+    :ref:`configuration` as well for details about how to use configuration
+    files.
+
+
+In-line Ignoring Errors
+=======================
+
+In some cases, we might not want to ignore an error code (or class of error
+codes) for the entirety of our project. Instead, we might want to ignore the
+specific error code on a specific line. Let's take for example a line like
+
+.. code-block:: python
+
+    example = lambda: 'example'
+
+Sometimes we genuinely need something this simple. We could instead define
+a function like we normally would. Note, in some contexts this distracts from
+what is actually happening. In those cases, we can also do:
+
+.. code-block:: python
+
+    example = lambda: 'example'  # noqa: E731
+
+This will only ignore the error from pycodestyle that checks for lambda
+assignments and generates an ``E731``. If there are other errors on the line
+then those will be reported.
+
+.. note::
+
+    If we ever want to disable |Flake8| respecting ``# noqa`` comments, we can
+    can refer to :option:`flake8 --disable-noqa`.
+
+If we instead had more than one error that we wished to ignore, we could
+list all of the errors with commas separating them:
+
+.. code-block:: python
+
+    # noqa: E731,E123
+
+Finally, if we have a particularly bad line of code, we can ignore every error
+using simply ``# noqa`` with nothing after it.
+
+
+Ignoring Entire Files
+=====================
+
+Imagine a situation where we are adding |Flake8| to a codebase. Let's further
+imagine that with the exception of a few particularly bad files, we can add
+|Flake8| easily and move on with our lives. There are two ways to ignore the
+file:
+
+#. By explicitly adding it to our list of excluded paths (see: :option:`flake8
+   --exclude`)
+
+#. By adding ``# flake8: noqa`` to the file
+
+The former is the **recommended** way of ignoring entire files. By using our
+exclude list, we can include it in our configuration file and have one central
+place to find what files aren't included in |Flake8| checks. The latter has the
+benefit that when we run |Flake8| with :option:`flake8 --disable-noqa` all of
+the errors in that file will show up without having to modify our
+configuration. Both exist so we can choose which is better for us.

docs/source/user/index.rst

@@ -0,0 +1,33 @@
+==============
+ Using Flake8
+==============
+
+|Flake8| can be used in many ways. A few:
+
+- invoked on the command-line
+
+- invoked via Python
+
+- called by Git or Mercurial on or around committing
+
+This guide will cover all of these and the nuances for using |Flake8|.
+
+.. note::
+
+    This portion of |Flake8|'s documentation does not cover installation. See
+    the :ref:`installation-guide` section for how to install |Flake8|.
+
+.. toctree::
+    :maxdepth: 2
+
+    invocation
+    configuration
+    options
+    ignoring-errors
+    using-plugins
+    python-api
+
+.. config files
+.. command-line tutorial
+.. VCS usage
+.. installing and using plugins

docs/source/user/invocation.rst

@@ -0,0 +1,144 @@
+.. _invocation:
+
+=================
+ Invoking Flake8
+=================
+
+Once you have :ref:`installed <installation-guide>` |Flake8|, you can begin
+using it. Most of the time, you will be able to generically invoke |Flake8|
+like so:
+
+.. prompt:: bash
+
+    flake8 ...
+
+Where you simply allow the shell running in your terminal to locate |Flake8|.
+In some cases, though, you may have installed |Flake8| for multiple versions
+of Python (e.g., Python 2.7 and Python 3.5) and you need to call a specific
+version. In that case, you will have much better results using:
+
+.. prompt:: bash
+
+    python2.7 -m flake8
+
+Or
+
+.. prompt:: bash
+
+    python3.5 -m flake8
+
+Since that will tell the correct version of Python to run |Flake8|.
+
+.. note::
+
+    Installing |Flake8| once will not install it on both Python 2.7 and
+    Python 3.5. It will only install it for the version of Python that
+    is running pip.
+
+It is also possible to specify command-line options directly to |Flake8|:
+
+.. prompt:: bash
+
+    flake8 --select E123
+
+Or
+
+.. prompt:: bash
+
+    python<version> -m flake8 --select E123
+
+.. note::
+
+    This is the last time we will show both versions of an invocation.
+    From now on, we'll simply use ``flake8`` and assume that the user
+    knows they can instead use ``python<version> -m flake8`` instead.
+
+It's also possible to narrow what |Flake8| will try to check by specifying
+exactly the paths and directories you want it to check. Let's assume that
+we have a directory with python files and sub-directories which have python
+files (and may have more sub-directories) called ``my_project``. Then if
+we only want errors from files found inside ``my_project`` we can do:
+
+.. prompt:: bash
+
+    flake8 my_project
+
+And if we only want certain errors (e.g., ``E123``) from files in that
+directory we can also do:
+
+.. prompt:: bash
+
+    flake8 --select E123 my_project
+
+If you want to explore more options that can be passed on the command-line,
+you can use the ``--help`` option:
+
+.. prompt:: bash
+
+    flake8 --help
+
+And you should see something like:
+
+.. code::
+
+    Usage: flake8 [options] file file ...
+
+    Options:
+      --version             show program's version number and exit
+      -h, --help            show this help message and exit
+      -v, --verbose         Print more information about what is happening in
+                            flake8. This option is repeatable and will increase
+                            verbosity each time it is repeated.
+      -q, --quiet           Report only file names, or nothing. This option is
+                            repeatable.
+      --count               Print total number of errors and warnings to standard
+                            error and set the exit code to 1 if total is not
+                            empty.
+      --diff                Report changes only within line number ranges in the
+                            unified diff provided on standard in by the user.
+      --exclude=patterns    Comma-separated list of files or directories to
+                            exclude.(Default:
+                            .svn,CVS,.bzr,.hg,.git,__pycache__,.tox)
+      --filename=patterns   Only check for filenames matching the patterns in this
+                            comma-separated list. (Default: *.py)
+      --format=format       Format errors according to the chosen formatter.
+      --hang-closing        Hang closing bracket instead of matching indentation
+                            of opening bracket's line.
+      --ignore=errors       Comma-separated list of errors and warnings to ignore
+                            (or skip). For example, ``--ignore=E4,E51,W234``.
+                            (Default: E121,E123,E126,E226,E24,E704)
+      --max-line-length=n   Maximum allowed line length for the entirety of this
+                            run. (Default: 79)
+      --select=errors       Comma-separated list of errors and warnings to enable.
+                            For example, ``--select=E4,E51,W234``. (Default: )
+      --disable-noqa        Disable the effect of "# noqa". This will report
+                            errors on lines with "# noqa" at the end.
+      --show-source         Show the source generate each error or warning.
+      --statistics          Count errors and warnings.
+      --enabled-extensions=ENABLED_EXTENSIONS
+                            Enable plugins and extensions that are otherwise
+                            disabled by default
+      --exit-zero           Exit with status code "0" even if there are errors.
+      -j JOBS, --jobs=JOBS  Number of subprocesses to use to run checks in
+                            parallel. This is ignored on Windows. The default,
+                            "auto", will auto-detect the number of processors
+                            available to use. (Default: auto)
+      --output-file=OUTPUT_FILE
+                            Redirect report to a file.
+      --append-config=APPEND_CONFIG
+                            Provide extra config files to parse in addition to the
+                            files found by Flake8 by default. These files are the
+                            last ones read and so they take the highest precedence
+                            when multiple files provide the same option.
+      --config=CONFIG       Path to the config file that will be the authoritative
+                            config source. This will cause Flake8 to ignore all
+                            other configuration files.
+      --isolated            Ignore all found configuration files.
+      --builtins=BUILTINS   define more built-ins, comma separated
+      --doctests            check syntax of the doctests
+      --include-in-doctest=INCLUDE_IN_DOCTEST
+                            Run doctests only on these files
+      --exclude-from-doctest=EXCLUDE_FROM_DOCTEST
+                            Skip these files when running doctests
+
+    Installed plugins: pyflakes: 1.0.0, pep8: 1.7.0

docs/source/user/options.rst

@@ -0,0 +1,730 @@
+.. _options-list:
+
+================================================
+ Full Listing of Options and Their Descriptions
+================================================
+
+..
+    NOTE(sigmavirus24): When adding new options here, please follow the
+    following _rough_ template:
+
+    .. option:: --<opt-name>[=<descriptive-name-of-parameter>]
+
+        Active description of option's purpose (note that each description
+        starts with an active verb)
+
+        Command-line usage:
+
+        .. prompt:: bash
+
+            flake8 --<opt-name>[=<example-parameter(s)>] [positional params]
+
+        This **can[ not]** be specified in config files.
+
+        (If it can be, an example using .. code-block:: ini)
+
+    Thank you for your contribution to Flake8's documentation.
+
+.. program:: flake8
+
+.. option:: --version
+
+    Show |Flake8|'s version as well as the versions of all plugins
+    installed.
+
+    Command-line usage:
+
+    .. prompt:: bash
+
+        flake8 --version
+
+    This **can not** be specified in config files.
+
+
+.. option:: -h, --help
+
+    Show a description of how to use |Flake8| and its options.
+
+    Command-line usage:
+
+    .. prompt:: bash
+
+        flake8 --help
+        flake8 -h
+
+    This **can not** be specified in config files.
+
+
+.. option::  -v, --verbose
+
+    Increase the verbosity of |Flake8|'s output. Each time you specify
+    it, it will print more and more information.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 -vv
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        verbose = 2
+
+
+.. option:: -q, --quiet
+
+    Decrease the verbosity of |Flake8|'s output. Each time you specify it,
+    it will print less and less information.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 -q
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        quiet = 1
+
+
+.. option:: --count
+
+    Print the total number of errors.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --count dir/
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        count = True
+
+
+.. option:: --diff
+
+    Use the unified diff provided on standard in to only check the modified
+    files and report errors included in the diff.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        git diff -u | flake8 --diff
+
+    This **can not** be specified in config files.
+
+
+.. option:: --exclude=<patterns>
+
+    Provide a comma-separated list of glob patterns to exclude from checks.
+
+    This defaults to: ``.svn,CVS,.bzr,.hg,.git,__pycache__,.tox``
+
+    Example patterns:
+
+    - ``*.pyc`` will match any file that ends with ``.pyc``
+
+    - ``__pycache__`` will match any path that has ``__pycache__`` in it
+
+    - ``lib/python`` will look expand that using :func:`os.path.abspath` and
+      look for matching paths
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --exclude=*.pyc dir/
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        exclude =
+            .tox,
+            __pycache__
+
+
+.. option:: --filename=<patterns>
+
+    Provide a comma-separate list of glob patterns to include for checks.
+
+    This defaults to: ``*.py``
+
+    Example patterns:
+
+    - ``*.py`` will match any file that ends with ``.py``
+
+    - ``__pycache__`` will match any path that has ``__pycache__`` in it
+
+    - ``lib/python`` will look expand that using :func:`os.path.abspath` and
+      look for matching paths
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --filename=*.py dir/
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        filename =
+            example.py,
+            another-example*.py
+
+
+.. option:: --stdin-display-name=<display_name>
+
+    Provide the name to use to report warnings and errors from code on stdin.
+
+    Instead of reporting an error as something like:
+
+    .. code::
+
+        stdin:82:73 E501 line too long
+
+    You can specify this option to have it report whatever value you want
+    instead of stdin.
+
+    This defaults to: ``stdin``
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        cat file.py | flake8 --stdin-display-name=file.py -
+
+    This **can not** be specified in config files.
+
+
+.. option:: --format=<format>
+
+    Select the formatter used to display errors to the user.
+
+    This defaults to: ``default``
+
+    By default, there are two formatters available:
+
+    - default
+    - pylint
+
+    Other formatters can be installed. Refer to their documentation for the
+    name to use to select them. Further, users can specify their own format
+    string. The variables available are:
+
+    - code
+    - col
+    - path
+    - row
+    - text
+
+    The default formatter has a format string of:
+
+    .. code-block:: python
+
+        '%(path)s:%(row)d:%(col)d: %(code)s %(text)s'
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --format=pylint dir/
+        flake8 --format='%(path)s::%(row)d,%(col)d::%(code)s::%(text)s' dir/
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        format=pylint
+        format=%(path)s::%(row)d,%(col)d::%(code)s::%(text)s
+
+
+.. option:: --hang-closing
+
+    Toggle whether pycodestyle should enforce matching the indentation of the
+    opening bracket's line. When you specify this, it will prefer that you
+    hang the closing bracket rather than match the indentation.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --hang-closing dir/
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        hang_closing = True
+        hang-closing = True
+
+
+.. option:: --ignore=<errors>
+
+    Specify a list of codes to ignore. The list is expected to be
+    comma-separated, and does not need to specify an error code exactly.
+    Since |Flake8| 3.0, this **can** be combined with :option:`--select`. See
+    :option:`--select` for more information.
+
+    For example, if you wish to only ignore ``W234``, then you can specify
+    that. But if you want to ignore all codes that start with ``W23`` you
+    need only specify ``W23`` to ignore them. This also works for ``W2`` and
+    ``W`` (for example).
+
+    This defaults to: ``E121,E123,E126,E226,E24,E704``
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --ignore=E121,E123 dir/
+        flake8 --ignore=E24,E704 dir/
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        ignore =
+            E121,
+            E123
+        ignore = E121,E123
+
+
+.. option:: --max-line-length=<n>
+
+    Set the maximum length that any line (with some exceptions) may be.
+
+    Exceptions include lines that are either strings or comments which are
+    entirely URLs. For example:
+
+    .. code-block:: python
+
+        # https://some-super-long-domain-name.com/with/some/very/long/path
+
+        url = (
+            'http://...'
+        )
+
+    This defaults to: 79
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --max-line-length 99 dir/
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        max-line-length = 79
+
+
+.. option:: --select=<errors>
+
+    Specify the list of error codes you wish |Flake8| to report. Similarly to
+    :option:`--ignore`. You can specify a portion of an error code to get all
+    that start with that string. For example, you can use ``E``, ``E4``,
+    ``E43``, and ``E431``.
+
+    This defaults to: E,F,W,C
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --select=E431,E5,W,F dir/
+        flake8 --select=E,W dir/
+
+    This can also be combined with :option:`--ignore`:
+
+    .. prompt:: bash
+
+        flake8 --select=E --ignore=E432 dir/
+
+    This will report all codes that start with ``E``, but ignore ``E432``
+    specifically. This is more flexibly than the |Flake8| 2.x and 1.x used
+    to be.
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        select =
+            E431,
+            W,
+            F
+
+
+.. option:: --disable-noqa
+
+    Report all errors, even if it is on the same line as a ``# NOQA`` comment.
+    ``# NOQA`` can be used to silence messages on specific lines. Sometimes,
+    users will want to see what errors are being silenced without editing the
+    file. This option allows you to see all the warnings, errors, etc.
+    reported.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --disable-noqa dir/
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        disable_noqa = True
+        disable-noqa = True
+
+
+.. option:: --show-source
+
+    Print the source code generating the error/warning in question.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --show-source dir/
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        show_source = True
+        show-source = True
+
+
+.. option:: --statistics
+
+    Count the number of occurrences of each error/warning code and
+    print a report.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --statistics
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        statistics = True
+
+
+.. option:: --enable-extensions=<errors>
+
+    Enable off-by-default extensions.
+
+    Plugins to |Flake8| have the option of registering themselves as
+    off-by-default. These plugins effectively add themselves to the
+    default ignore list.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --enable-extensions=H111 dir/
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        enable-extensions =
+            H111,
+            G123
+        enable_extensions =
+            H111,
+            G123
+
+
+.. option:: --exit-zero
+
+    Force |Flake8| to use the exit status code 0 even if there are errors.
+
+    By default |Flake8| will exit with a non-zero integer if there are errors.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --exit-zero dir/
+
+    This **can not** be specified in config files.
+
+
+.. option:: --install-hook=VERSION_CONTROL_SYSTEM
+
+    Install a hook for your version control system that is executed before
+    or during commit.
+
+    The available options are:
+
+    - git
+    - mercurial
+
+    Command-line usage:
+
+    .. prompt:: bash
+
+        flake8 --install-hook=git
+        flake8 --install-hook=mercurial
+
+    This **can not** be specified in config files.
+
+
+.. option:: --jobs=<n>
+
+    Specify the number of subprocesses that |Flake8| will use to run checks in
+    parallel.
+
+    .. note::
+
+        This option is ignored on Windows because :mod:`multiprocessing` does
+        not support Windows across all supported versions of Python.
+
+    This defaults to: ``auto``
+
+    The default behaviour will use the number of CPUs on your machine as
+    reported by :func:`multiprocessing.cpu_count`.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --jobs=8 dir/
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        jobs = 8
+
+
+.. option:: --output-file=<path>
+
+    Redirect all output to the specified file.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --output-file=output.txt dir/
+        flake8 -vv --output-file=output.txt dir/
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        output-file = output.txt
+        output_file = output.txt
+
+
+.. option:: --append-config=<config>
+
+    Provide extra config files to parse in after and in addition to the files
+    that |Flake8| found on its own. Since these files are the last ones read
+    into the Configuration Parser, so it has the highest precedence if it
+    provides an option specified in another config file.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --append-config=my-extra-config.ini dir/
+
+    This **can not** be specified in config files.
+
+
+.. option:: --config=<config>
+
+    Provide a path to a config file that will be the only config file read and
+    used. This will cause |Flake8| to ignore all other config files that
+    exist.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --config=my-only-config.ini dir/
+
+    This **can not** be specified in config files.
+
+
+.. option:: --isolated
+
+    Ignore any config files and use |Flake8| as if there were no config files
+    found.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --isolated dir/
+
+    This **can not** be specified in config files.
+
+
+.. option:: --builtins=<builtins>
+
+    Provide a custom list of builtin functions, objects, names, etc.
+
+    This allows you to let pyflakes know about builtins that it may
+    not immediately recognize so it does not report warnings for using
+    an undefined name.
+
+    This is registered by the default PyFlakes plugin.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --builtins=_,_LE,_LW dir/
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        builtins =
+            _,
+            _LE,
+            _LW
+
+
+.. option:: --doctests
+
+    Enable PyFlakes syntax checking of doctests in docstrings.
+
+    This is registered by the default PyFlakes plugin.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --doctests dir/
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        doctests = True
+
+
+.. option:: --include-in-doctest=<paths>
+
+    Specify which files are checked by PyFlakes for doctest syntax.
+
+    This is registered by the default PyFlakes plugin.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --include-in-doctest=dir/subdir/file.py,dir/other/file.py dir/
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        include-in-doctest =
+            dir/subdir/file.py,
+            dir/other/file.py
+        include_in_doctest =
+            dir/subdir/file.py,
+            dir/other/file.py
+
+
+.. option:: --exclude-from-doctest=<paths>
+
+    Specify which files are not to be checked by PyFlakes for doctest syntax.
+
+    This is registered by the default PyFlakes plugin.
+
+    Command-line example:
+
+    .. prompt:: bash
+
+        flake8 --exclude-in-doctest=dir/subdir/file.py,dir/other/file.py dir/
+
+    This **can** be specified in config files.
+
+    Example config file usage:
+
+    .. code-block:: ini
+
+        exclude-in-doctest =
+            dir/subdir/file.py,
+            dir/other/file.py
+        exclude_in_doctest =
+            dir/subdir/file.py,
+            dir/other/file.py
+
+
+.. option:: --benchmark
+
+    Collect and print benchmarks for this run of |Flake8|. This aggregates the
+    total number of:
+
+    - tokens
+    - physical lines
+    - logical lines
+    - files
+
+    and the number of elapsed seconds.
+
+    Command-line usage:
+
+    .. prompt:: bash
+
+        flake8 --benchmark dir/
+
+    This **can not** be specified in config files.

docs/source/user/python-api.rst

@@ -0,0 +1,11 @@
+===================
+ Public Python API
+===================
+
+|Flake8| 3.0.0 presently does not have a public, stable Python API.
+
+When it does it will be located in :mod:`flake8.api` and that will
+be documented here.
+
+.. automodule:: flake8.api
+    :members:

docs/source/user/using-plugins.rst

@@ -0,0 +1,66 @@
+==================================
+ Using Plugins For Fun and Profit
+==================================
+
+|Flake8| is useful on its own but a lot of |Flake8|'s popularity is due to
+its extensibility. Our community has developed :term:`plugin`\ s that augment
+|Flake8|'s behaviour. Most of these plugins are uploaded to PyPI_. The
+developers of these plugins often have some style they wish to enforce.
+
+For example, `flake8-docstrings`_ adds a check for :pep:`257` style
+conformance. Others attempt to enforce consistency, like `flake8-future`_.
+
+.. note::
+
+    The accuracy or reliability of these plugins may vary wildly from plugin
+    to plugin and not all plugins are guaranteed to work with |Flake8| 3.0.
+
+To install a third-party plugin, make sure that you know which version of
+Python (or pip) you used to install |Flake8|. You can then use the most
+appropriate of:
+
+.. prompt:: bash
+
+    pip install <plugin-name>
+    pip3 install <plugin-name>
+    python -m pip install <plugin-name>
+    python2.7 -m pip install <plugin-name>
+    python3 -m pip install <plugin-name>
+    python3.4 -m pip install <plugin-name>
+    python3.5 -m pip install <plugin-name>
+
+To install the plugin, where ``<plugin-name>`` is the package name on PyPI_.
+To verify installation use:
+
+.. prompt:: bash
+
+    flake8 --version
+    python<version> -m flake8 --version
+
+To see the plugin's name and version in the output.
+
+.. seealso:: :ref:`How to Invoke Flake8 <invocation>`
+
+After installation, most plugins immediately start reporting :term:`error`\ s.
+Check the plugin's documentation for which error codes it returns and if it
+disables any by default.
+
+.. note::
+
+    You can use both :option:`flake8 --select` and :option:`flake8 --ignore`
+    with plugins.
+
+Some plugins register new options, so be sure to check :option:`flake8 --help`
+for new flags and documentation. These plugins may also allow these flags to
+be specified in your configuration file. Hopefully, the plugin authors have
+documented this for you.
+
+.. seealso:: :ref:`Configuring Flake8 <configuration>`
+
+
+.. _PyPI:
+    https://pypi.io/
+.. _flake8-docstrings:
+    https://pypi.io/project/flake8-docstrings/
+.. _flake8-future:
+    https://pypi.io/project/flake8-future/