[PATCH 2 of 7 v3 flags] fancyopts: disallow true as a boolean flag default (API)
pierre-yves.david at ens-lyon.org
Fri Sep 16 10:29:17 EDT 2016
On 09/16/2016 04:21 PM, Augie Fackler wrote:
>> On Sep 16, 2016, at 09:48, Pierre-Yves David <pierre-yves.david at ens-lyon.org> wrote:
>> On 09/14/2016 05:11 AM, Augie Fackler wrote:
>>> # HG changeset patch
>>> # User Augie Fackler <augie at google.com>
>>> # Date 1472584421 14400
>>> # Tue Aug 30 15:13:41 2016 -0400
>>> # Node ID 828f260114a3a55e246cb5de434e75bdc782e4ad
>>> # Parent 600be3c9acee0ec14bd19c032cc0480e4501fe8c
>>> fancyopts: disallow true as a boolean flag default (API)
>>> This was nonsense, as there's not been a way for the user to
>>> un-specify the flag. Restricting this behavior will open the door to
>>> some nice fit-and-finish functionality in a later patch, and shouldn't
>>> break any third party extensions. This is marked as (API) since it
>>> might break a third party extension, but given the fact that it was
>>> silly before that's mostly a formality.
>> I really wish we had details on this as requested in the review of the previous version. Especially because I remember that forbidding 'True' as default was making other improvement hard so I'm not sure why we have to do this.
> Err? I'm not sure what you're asking for now, and I definitely didn't understand it on the last go round.
Okay, let me clarified, My question here is:
Why is this problematic to have default to 'True Value'
You refered this as """These cases are a bit problematic, because we
don't really have a way to specify default-true flags""" in
I'm seeing another avatar of this question when you says "Restricting
this behavior will open the door to some nice fit-and-finish
functionality in a later patch" in the current thread. I would like
details on this "nice fit-and-finish" features.
Does this clarify my question ?
>>> Due to how early parsing of global options works, we have to add some
>>> extra coupling between fancyopts and dispatch so that we can provide a
>>> "default" of True for already-parsed boolean flags when doing
>>> command-level flag parsing.
>>> diff --git a/mercurial/dispatch.py b/mercurial/dispatch.py
>>> --- a/mercurial/dispatch.py
>>> +++ b/mercurial/dispatch.py
>>> @@ -555,7 +555,10 @@ def _parse(ui, args):
>>> # combine global options into local
>>> for o in commands.globalopts:
>>> - c.append((o, o, options[o], o))
>>> + # Passing a tuple of length six through into the option parser
>>> + # allows otherwise-illegal defaults to survive, which is how
>>> + # we handle global options like --quiet.
>>> + c.append((o, o, options[o], o, '', True))
>>> args = fancyopts.fancyopts(args, c, cmdoptions, gnu=True)
>>> diff --git a/mercurial/fancyopts.py b/mercurial/fancyopts.py
>>> --- a/mercurial/fancyopts.py
>>> +++ b/mercurial/fancyopts.py
>>> @@ -79,10 +79,22 @@ def fancyopts(args, options, state, gnu=
>>> alllong = set(o for o in options)
>>> for option in options:
>>> - if len(option) == 5:
>>> + boolok = False
>>> + if len(option) == 6:
>>> + # If the tuple is of length 6, then it's a global option
>>> + # that was already parsed, so we're really just passing
>>> + # its "default" through the second phase of flags parsing
>>> + # (for command-level flags). As a result, we have to allow
>>> + # defaults of True and not rewrite defaults of False.
>>> + short, name, default, comment, dummy, dummy = option
>>> + boolok = True
>>> + elif len(option) == 5:
>>> short, name, default, comment, dummy = option
>>> short, name, default, comment = option
>>> + if default is True and not boolok:
>>> + raise ValueError('fancyopts does not support default-true '
>>> + 'boolean flags: %r' % name)
>> As pointed in a previous review, identity testing to boolean really raise red flag here. I see this as a significant sign of a bad idea and something we should avoid at all cost.
> Calm down - this isn't the one that was pointed out in the past, and I didn't notice this one as I was doing reworks for v3. I don't disagree with your opinion here.
Don't worry, I'm not mad, just a bit puzzled ☺ I'm happy to learn we
actually agree here.
> It sounds like you should be mailing a check-code rule about 'is (True|False)' to forbid this pattern.
Yep, as we have a consensus to ban them, check-code seems something we
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