Add indent-size option

src/flake8/defaults.py

@@ -24,6 +24,7 @@ IGNORE = (
 )
 SELECT = ('E', 'F', 'W', 'C90')
 MAX_LINE_LENGTH = 79
+INDENT_SIZE = 4
 
 TRUTHY_VALUES = set(['true', '1', 't'])
 

src/flake8/main/options.py

@@ -19,6 +19,7 @@ def register_default_options(option_manager):
     - ``--hang-closing``
     - ``--ignore``
     - ``--max-line-length``
+    - ``--indent-size``
     - ``--select``
     - ``--disable-noqa``
     - ``--show-source``
@@ -115,6 +116,12 @@ def register_default_options(option_manager):
              '(Default: %default)',
     )
 
+    add_option(
+        '--indent-size', type='int', metavar='n',
+        default=defaults.INDENT_SIZE, parse_from_config=True,
+        help='Number of spaces used for indentation (Default: %default)',
+    )
+
     add_option(
         '--select', metavar='errors', default=','.join(defaults.SELECT),
         parse_from_config=True, comma_separated_list=True,

src/flake8/processor.py

@@ -76,6 +76,8 @@ class FileProcessor(object):
         self.indent_char = None
         #: Current level of indentation
         self.indent_level = 0
+        #: Number of spaces used for indentation
+        self.indent_size = options.indent_size
         #: Line number in the file
         self.line_number = 0
         #: Current logical line