[Python-Dev] configparser: __name__ special key is mad (original) (raw)

Łukasz Langa lukasz at langa.pl
Fri Jul 30 21:24:09 CEST 2010

Hello guys, I want to sum up all strange things about the behaviour of __name__, a special key present in every section of a parser instance.

Hopefully it will be removed at once or in the worst case oficially deprecated and removed in 3.4.

  1. There is a special __name__ key in every section.
  2. Except for the DEFAULTSECT.
  3. __name__ key is set for every section read from a file.
  4. and not when adding by add_section().
  5. if __name__ does exist, it's not visible in parser.options('section')
  6. but it is here: parser.has_option('section', '__name__') == True
  7. and can be obtained by parser.get('section', '__name__')
  8. and can be changed by parser.set('section', '__name__', 'ANY VALUE')
  9. and can be removed by parser.remove_option('section', '__name__')
  10. even if the value is changed by parser.set(), it won't be written back to a file with parser.write()

All this looks like a feature that was not particularly complete and well defined when it was first created. Or possibly, it became rotten with time and now nobody is using it anyway. That way or the other, I couldn't come up with a valid use case for __name__ with the current implementation. It doesn't serve any internal purpose and the only way you can actually get it is to parser.get('section', '__name__') which returns 'section' anyway. About as useless as it gets. Of course, one can go and take the internal parser._sections data structure of the parser but that's evil.

If I were to say what to do with all this, I'd simply remove all mentions of a special __name__ key in configparser.py. I know that your default answer for that kind of idea is "no, backwards compatibility for the win". And I agree with that. In this case however we have a concept that is so broken that you can't actually use it.

Many of you are here for quite a long time, maybe someone can shed some light on this. Maybe I'm missing something.

-- Best regards, Łukasz Langa tel. +48 791 080 144 WWW http://lukasz.langa.pl/

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