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Re: [Qemu-devel] [PATCH for-2.11 v2 1/5] qmp-shell: Use optparse module
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH for-2.11 v2 1/5] qmp-shell: Use optparse module |
Date: |
Fri, 18 Aug 2017 16:42:00 +0100 |
User-agent: |
Mutt/1.8.3 (2017-05-23) |
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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[Qemu-devel] [PATCH for-2.11 v2 2/5] qmp-shell: Pass split cmdargs to __build_cmd(), Eduardo Habkost, 2017/08/08
[Qemu-devel] [PATCH for-2.11 v2 3/5] qmp-shell: execute_cmdargs() method, Eduardo Habkost, 2017/08/08
[Qemu-devel] [PATCH for-2.11 v2 4/5] qmp-shell: Accept QMP command as argument, Eduardo Habkost, 2017/08/08