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Re: Variable arguments (*args, **kwargs): seeking elegance

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John Ladasky wrote:

> Hi folks,
> 
> I'm trying to make some of Python class definitions behave like the ones I
> find in professional packages, such as Matplotlib.  A Matplotlib class can
> often have a very large number of arguments -- some of which may be
> optional, some of which will assume default values if the user does not
> override them, etc.

Personally, I'd rather not copy that kind of interface.

> I have working code which does this kind of thing.  I define required
> arguments and their default values as a class attribute, in an
> OrderedDict, so that I can match up defaults, in order, with *args.  I'm
> using set.issuperset() to see if an argument passed in **kwargs conflicts
> with one which was passed in *args.  I use  set.isdisjoint() to look for
> arguments in **kwargs which are not expected by the class definition,
> raising an error if such arguments are found.

Why do you rely on a homebrew solution instead of actually calling the 
function or initializer?

> Even though my code works, I'm finding it to be a bit clunky.  And now,
> I'm writing a new class which has subclasses, and so actually keeps the
> "extra" kwargs instead of raising an error... This is causing me to
> re-evaluate my original code.
> 
> It also leads me to ask: is there a CLEAN and BROADLY-APPLICABLE way for
> handling the *args/**kwargs/default values shuffle that I can study?  Or
> is this sort of thing too idiosyncratic for there to be a general method?
> 
> Thanks for any pointers!

inspect.getcallargs() may be worth a look.

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Thread

Variable arguments (*args, **kwargs): seeking elegance John Ladasky <john_ladasky@sbcglobal.net> - 2013-10-05 21:04 -0700
  Re: Variable arguments (*args, **kwargs): seeking elegance Peter Otten <__peter__@web.de> - 2013-10-06 09:25 +0200
  Re: Variable arguments (*args, **kwargs): seeking elegance Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-06 14:34 -0700
  Re: Variable arguments (*args, **kwargs): seeking elegance Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-07 02:43 +0000
    Re: Variable arguments (*args, **kwargs): seeking elegance Skip Montanaro <skip@pobox.com> - 2013-10-07 08:52 -0500
  Re: Variable arguments (*args, **kwargs): seeking elegance John Ladasky <john_ladasky@sbcglobal.net> - 2013-10-07 09:26 -0700
    Re: Variable arguments (*args, **kwargs): seeking elegance John Ladasky <john_ladasky@sbcglobal.net> - 2013-10-07 09:42 -0700
    Re: Variable arguments (*args, **kwargs): seeking elegance Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-10-07 21:13 +0000
      Re: Variable arguments (*args, **kwargs): seeking elegance John Ladasky <john_ladasky@sbcglobal.net> - 2013-10-07 14:49 -0700
  Re: Variable arguments (*args, **kwargs): seeking elegance Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-07 14:12 -0700
  Re: Variable arguments (*args, **kwargs): seeking elegance Peter Cacioppi <peter.cacioppi@gmail.com> - 2013-10-08 01:30 -0700

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