[PATCH 3 of 3] revset: drop factory that promotes spanset to fullreposet

[Yuya Nishihara]

On Sun, 17 May 2015 20:12:50 -0700, Pierre-Yves David wrote:
> On 05/14/2015 04:01 PM, Yuya Nishihara wrote:
> > On Wed, 13 May 2015 22:58:16 -0700, Pierre-Yves David wrote:
> >> On 05/06/2015 02:00 AM, Yuya Nishihara wrote:
> >>> On Wed, 06 May 2015 00:11:50 -0700, Pierre-Yves David wrote:
> >>>> On related topic, one what behavior did we settle regarding usage of
> >>>> "null" in revset? I cannot find anything related to this discussion in
> >>>> mercurial/revset.py
> >>>
> >>> Not sure if it's settled. My starting point was to fix buggy handling of
> >>> "null" in revset.
> >>>
> >>> http://thread.gmane.org/gmane.comp.version-control.mercurial.devel/75134/focus=75148
> >>
> >> We should probably discuss this, decide on a behavior, document it and
> >> stick to it. I cannot access the gmane thread for some reason :-/. Do
> >> you have another pointer to this messages?
> >>
> >> My current opinions is:
> >>
> >> - null should work when explicitly referenced
> >> - null should not survive combination (and) with anything.
> >
> > I agree with the bullet point 1, but my opinion for 2 is:
> >
> > - null should work just like other revisions once appeared
> >
> >> In practice this means
> >>
> >> 1) The following include null in the result
> >> - "null"
> >> - "null + 2"
> >> - "null::" (probably)
> >> - "::null" (probably)
> >>
> >> 2) the following does not includes it
> >> - "null and (::2)"
> >> - "null and date(-9001)"
> >> - "null and all()"
> >> (replaces null by any of the variant in (1))
> >>
> >> Same should probably apply to the "working directory" revset.
> >> "all()" could maybe take and argument to accept null.
> >
> > - "null and (:2)" -> ()       # because :2 = 0:2
> > - "null and (::2)" -> (null,)
> > - "null and date(-100000)" -> (null,)
> > - "null and all()" -> ()      # if all() = 0:tip
> >                     or (null)  # if all() = everything in sets (like "and true")
> > - "wdir() and draft()" -> (wdir,)
> 
> So, there does not seems to be an obvious consensus and the question 
> seems to be complicated. I think we need to take a global look at this 
> issue to ensure we have something consistent in 3.5. This is especially 
> important if we want to push the 'wdir()' forward.
> 
> I think we need to start a wiki page at this point. The wiki page would 
> list:
> 
> - a set of relevant example usecases. With possible behavior.
> - sorts -all- existing revset is a set of relevant categories taking in 
> account how they are affected by null/wdir and if their implementation 
> would need rework to support them.
> 
> Yuya, do you have time/willingness to build such wiki page?

will do.

> On the implementation front, revset are currently not ready for a
> consistent support of null/wdir. We would probably need a special flag
> to force specific inclusive "mode" for most revset predicate.

Perhaps your suggestion, "null should not survive", assumes a flag-based
implementation. I have another idea to handle null/wdir just like a normal
revision, in which "null should not survive" wouldn't go well.

Regards,