[Mesa-dev] glapi: use only one kind of argument parser in python generators

[Dylan Baker]

This is a small slice of a larger series I'm working on with the end
goal of using mako, the khronos XML, and being python3 compatible with
our generators. That series is over 100 patches already, and not even
finished with the first step of using mako. I've sent this out to get
some patches landed.

I've tested this with python 2.7 and 2.6. There is the catch that
argparse became part of the standard library in 2.7, so 2.6 users will
need to install argparse themselves, either with pip (pip install
argparse) or via their package manager (most distros with python 2.6
package this). It seems to me that since python 2.6 was deprecated in
octobor of 2013 it seem silly to support anything older (which would
have a deprecation date in 2012 or before), and widens the gap between
python 2 and python 3 both feature wise and syntax wise.

Currently we use a mixture of getopt, optparse, and raw sys.argv munging
to get command line arguments. Argparse is the de facto standard for
python programs, it's clean, powerful, easy to understand, and it does
everything in one place. It doesn't allow a usage() function to drift
out of sync from the actual implementation, since the majority of the
help message is auto generated, and the rest is part of the actual
definition.

This also moves to using the standard python idiom of a main() function
called in the 'if __name__ == "__main__"' guard. This is an extremely
common pattern, and it makes the code much cleaner.

This is available on freedesktop.org:
git://people.freedesktop.org/~dbaker/mesa submit/generator-argparse