[PATCH] shelve: adds restoring newly created branch (issue5048)

[Piotr Listkiewicz]

>
> You are Touching the shelve format. How did you ensure backward
> compatibility with (1) shelve created with older mercurial version (2)
> older version reading your new shelve format ?
> I can see other way that a format update to store this data. But if you
> format change does not have compatibility issue, it seems like a legit path.


Older version of mercurial will not have any problems with changes in
shelve format because new format only adds line to old format - so older
versions of mercurial will not read those lines and they will not restore
branch.

Other way around (new version of mercurial reading old version of shelve)
there is a problem because shelvedstate compares if versions are identical
with:

class shelvedstate(object):
    _version = 1
    _filename = 'shelvedstate'

    @classmethod
    def load(cls, repo):
        fp = repo.vfs(cls._filename)
        try:
            version = int(fp.readline().strip())

            if version != cls._version:
                raise error.Abort(_('this version of shelve is incompatible
'
                                   'with the version used in this repo'))

If version compability would be check with version <= cls._version there
wouldn't be any problems: for older version of format we wouldn't read
restorebranch information and we wound't be doing any branch restoring.

For now the only solution i see that wouldn't break previous compability
would be to try to read restore branch information and if it failed(with
IOError) it would assume restore branch should not take place.

I am looking forward to suggestions what to do with this problem.

>
> Could we check this before committing instead? Would that make it easier?


I have no idea how this would make it easier.


2016-02-22 16:28 GMT+01:00 Yuya Nishihara <yuya at tcha.org>:

> On Mon, 22 Feb 2016 16:13:43 +0100, Piotr Listkiewicz wrote:
> > > Can it be a single "branch-name-should-be-set" field? I feel the string
> > > 'True'
> > > is a bit ugly.
> >
> >  Could you be more descriptive, i have no idea how should it be done more
> > properly.
>
> I meant it could be ''|newbranch instead of (restorebranch,
> origshelvebranch)
> pair.
>
> That said, histedit saves boolean as 'True' or 'False', so it would be okay
> to store "restorebranch" as a string if it makes things easy.
>
> > > Perhaps we'd better to say "marked working directory as branch %s"
> again.
> >
> > Just ui.write("marked working directory as branch %s" % origshelvebranch)
> > would be ok?
>
> ui.status(_(...)). See commands.branch().
>
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