Allow disabling extended blank lines check

[benjaminjkraft]

It would be nice to have an option to disable all of the features where autopep8 goes beyond what pycodestyle requires. This is useful for avoiding spurious diffs when operating on existing codebases which don't necessarily follow those rules. Right now, they can only be disabled by disabling all the E301/E303 fixes, which is unfortunate.

[hhatto]

Hi,

Now how do you specify options and if you change, for example, what options should I have?

[benjaminjkraft]

For my purposes any of the following would work great:

• a special commandline flag, say --pycodestyle-only, that says to only do things that pycodestyle requires.
• separate error codes for these extra errors, so that I could ignore them using the usual mechanisms (e.g. --ignore which is what I am doing as a workaround, or better add them to the repo's .flake8 -- this is how other options are specified in this repo)
• convincing pycodestyle to upstream the added checks, although that's perhaps a slower process.

[hhatto]

autopep8 is correcting according to pycodestyle's error codes. Currently there are some to fix with lib2to3.

all of the features where autopep8 goes beyond what pycodestyle requires.

Specifically, what kind of correction is it? I would appreciate it if you have code examples.

[benjaminjkraft]

The corrections I refer to are the ones here: https://github.com/hhatto/autopep8/blob/master/autopep8.py#L187 which are using the same error code as pycodestyle but making different changes.

Here's a sample file:

# test.py
class Foo:
    """docstring"""
    def bar(self):
        pass

Running flake8 test.py returns no warnings, but autopep8 still tries to make changes:

$ autopep8 -d test.py
--- original/test.py
+++ fixed/test.py
@@ -1,5 +1,6 @@
 # test.py
 class Foo:
     """docstring"""
+
     def bar(self):
         pass