OSDev.org

I have a hard time following the Python PEP 8 when it comes to the naming convention:

Function names should be lowercase, with words separated by underscores as necessary to improve readability.

mixedCase is allowed only in contexts where that's already the prevailing style (e.g. threading.py), to retain backwards compatibility.

Yet we see countless times in python where they break their own guild lines:
str.startswith()
file.readlines()
etc..

I like to use camelCase for my function names, and I see no issue with others using lower_case, but I fail to understand how PEP8 can require us to use 'lower_case' when python itself uses 'lowercase' (no underscore) in many situations.

Just rambling,
Trevor

Probably for the same reason that they allow mixedCase- for backwards compatibility. They just want as much code as is reasonable to have the same style, for consistency.

Yet we see countless times in python where they break their own guild lines:
str.startswith()
file.readlines()
etc..

Probably underscores weren't deemed necessary to improve readability in this cases.

PEP 8 is a recommendation, not a law. What's important is the spirit.
Also see - if you haven't - the PyCon talk: Beyond PEP 8 by Raymond Hettinger.