Re: [Qemu-devel] [PATCH for-2.11 v2 1/5] qmp-shell: Use optparse module

[Stefan Hajnoczi]

On Tue, Aug 15, 2017 at 05:06:46PM -0300, Eduardo Habkost wrote:
> On Tue, Aug 15, 2017 at 10:56:07AM +0100, Daniel P. Berrange wrote:
> > On Tue, Aug 15, 2017 at 11:47:28AM +0200, Markus Armbruster wrote:
> > > Eduardo Habkost <address@hidden> 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
> 
> What about:
> 
>   try:
>       import argparse
>   except:
>       from thirdparty import argparse
> 
> (I think we could move all our Python modules [qemu.py, qmp.py]
> to ./scripts/qemu/, so this would become "qemu.thirdparty").
> 
> > 
> > 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.
> 
> Sounds good to me.

Sounds good.

Stefan

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