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Re: [Qemu-devel] [PATCH v4 1/2] qemu.py: make 'args' public
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH v4 1/2] qemu.py: make 'args' public |
Date: |
Wed, 26 Jul 2017 18:35:43 +0100 |
User-agent: |
Mutt/1.8.3 (2017-05-23) |
On Tue, Jul 25, 2017 at 11:30:16AM -0400, Cleber Rosa wrote:
> On 07/25/2017 09:37 AM, Stefan Hajnoczi wrote:
> > On Mon, Jul 24, 2017 at 02:44:37PM +0200, Amador Pahim wrote:
> >> Signed-off-by: Amador Pahim <address@hidden>
> >> Reviewed-by: Fam Zheng <address@hidden>
> >> ---
> >> scripts/qemu.py | 10 +++++-----
> >> tests/qemu-iotests/iotests.py | 18 +++++++++---------
> >> 2 files changed, 14 insertions(+), 14 deletions(-)
> >
> > Please don't do this, it encourages code duplication. Now arbitrary
> > users can start accessing the public field directly instead of adding a
> > reusable interfaces like add_monitor_telnet(), add_fd(), etc.
> >
>
> Judging from tests/qemu-iotests/iotests.py:VM and your comment above, I
> assume you see value in simple wrappers such as:
>
> def add_device(self, opts):
> self._args.append('-device')
> self._args.append(opts)
> return self
>
> I honestly do not see any value here. I do see value in other wrappers,
> such as add_drive(), in which default values are there for convenience,
> and a drive count is kept. In the end, my point is that the there are
> cases when a wrapper is just an annoyance and provides nothing more than
> the illusion of a better design.
I don't see much value in simple wrappers either besides method chaining
(more on that below).
Getting back to this patch, I can only review patches in the context of
the current code base. I don't know future plans you may have. The
change may make sense together with other new changes that use a public
args field in a useful way - it just doesn't make sense the way it has
been presented in isolation.
About method chaining, the current code seems to be written with method
chaining in mind:
https://en.wikipedia.org/wiki/Method_chaining#Python
If all arguments are methods then everything can be chained:
(vm.add_fd(fd.fileno(), 1, 'image0')
.add_drive('fd:image0', interface='none')
.add_device('virtio-blk-pci,drive=drive0'))
So I guess there is a small value in having add_device(). That said,
tests don't take advantage of method chaining much.
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- [Qemu-devel] [PATCH v4 0/2] scripts/qemu.py fixes and cleanups, Amador Pahim, 2017/07/24
- [Qemu-devel] [PATCH v4 1/2] qemu.py: make 'args' public, Amador Pahim, 2017/07/24
- Re: [Qemu-devel] [PATCH v4 1/2] qemu.py: make 'args' public, Stefan Hajnoczi, 2017/07/25
- Re: [Qemu-devel] [PATCH v4 1/2] qemu.py: make 'args' public, Amador Pahim, 2017/07/25
- Re: [Qemu-devel] [PATCH v4 1/2] qemu.py: make 'args' public, Cleber Rosa, 2017/07/25
- Re: [Qemu-devel] [PATCH v4 1/2] qemu.py: make 'args' public,
Stefan Hajnoczi <=
- Re: [Qemu-devel] [PATCH v4 1/2] qemu.py: make 'args' public, Cleber Rosa, 2017/07/26
- Re: [Qemu-devel] [PATCH v4 1/2] qemu.py: make 'args' public, Amador Pahim, 2017/07/27
- Re: [Qemu-devel] [PATCH v4 1/2] qemu.py: make 'args' public, Amador Pahim, 2017/07/27
[Qemu-devel] [PATCH v4 2/2] qemu.py: cleanup and fixes, Amador Pahim, 2017/07/24