On Tue, Aug 15, 2017 at 11:47:28AM +0200, Markus Armbruster wrote:
> Eduardo Habkost <ehabk...@redhat.com> writes:
>
> > It makes command-line parsing and generation of help text much
> > simpler.
>
> There's really no excuse for parsing command line arguments by hand in
> Python.
>
> > The optparse module is deprecated since Python 2.7, but argparse
> > is not available in Python 2.6 (the minimum Python version
> > required for building QEMU).
>
> We have a few uses of argparse in the tree. Are they okay?
>
> We also use getopt in places. Perhaps we should pick one way to parse
> command lines and stick to it.
I just came up against this problem with keycodemapdb which I'm adding as
a submodule to qemu. I used argparse there because it is the modern
recommended API for python >= 2.7. I examined possibilty of using
optparse instead, but it lacks key features - in particular the idea
of 'subcommands' is entirely missing from optparse.
The 'argparse' module is part of python core, but is *also* available
as a standalone module that is implemented in terms of optparse.
So, I would suggest that we just copy the 'argparse' module into the
QEMU 'scripts/thirdparty' directory.
Then in any files which need argparse, you can do this
try:
import argparse
except:
import os, sys
sys.path.append(os.path.join(os.path.dirname(__file__), "thirdparty"))
import argparse
so that it tries to use the argparse provided by python, and falls back
to pulling in the one in our scripts/thirdparty directory.
When we finally bump our min python to 2.7, we can simply drop this
compat code for the import statement. This avoids need for us to
re-write code to use a deprecated API, with a worse feature set.
Regards,
Daniel
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