Re: [PATCH] Add code to Mercurial VCS backend to show topic if there is any.

[Manuel Jacob <me@xxxxxxxxxxxxxx>]

Hi Daniel,

On 2020-06-07 14:14, Daniel Shahaf wrote:
> Manuel Jacob wrote on Sun, 07 Jun 2020 09:44 +0200:
> > "Topics" is an experimental concept in Mercurial that augments the
> > current branching concept (called "named branches").
> >
> > For more information, see the not always up-to-date Mercurial Wiki 
> > page
> > https://www.mercurial-scm.org/wiki/TopicPlan.
>
> I assume "experimental" means "future releases of Mercurial are not
> promised to be backwards compatible with the current design".

It is not yet part of Mercurial itself, but developed separately as an 
extension under the Mercurial project roof.

> Is the .hg/topic file name and data format set in stone yet?
>
> What if zsh 5.9 is released and then the Mercurial developers change
> the design to make .hg/topic a directory, and release _that_?  Then
> everyone who uses zsh 5.9 with hg will be stuck with vcs_info errors
> until their distro upgrades to newer zsh.

The .hg/topic file works very similar to the .hg/branch file (which is 
stable since 2007 and which zsh currently depends on). I can't think of 
any reason why someone would consider changing the format.

The file would only be created if a user installs and activates the 
extension, and explictly creates a topic (a specific kind of feature 
branch), so that makes it even more unlikely that something breaks.

> Cheers,
>
> Daniel
>
> > ---
> >  Functions/VCS_Info/Backends/VCS_INFO_get_data_hg | 10 +++++++++-
> >  1 file changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/Functions/VCS_Info/Backends/VCS_INFO_get_data_hg 
> > b/Functions/VCS_Info/Backends/VCS_INFO_get_data_hg
> > index cd5ef321d..e898f7298 100644
> > --- a/Functions/VCS_Info/Backends/VCS_INFO_get_data_hg
> > +++ b/Functions/VCS_Info/Backends/VCS_INFO_get_data_hg
> > @@ -5,7 +5,7 @@
> >
> >  setopt localoptions extendedglob NO_shwordsplit
> >
> > -local hgbase bmfile branchfile rebasefile dirstatefile mqseriesfile \
> > +local hgbase bmfile branchfile topicfile rebasefile dirstatefile 
> > mqseriesfile \
> >      curbmfile curbm \
> >      mqstatusfile mqguardsfile patchdir mergedir \
> >      r_csetid r_lrev r_branch i_bmhash i_bmname \
> > @@ -27,6 +27,7 @@ mergedir="${hgbase}/.hg/merge/"
> >  bmfile="${hgbase}/.hg/bookmarks"
> >  curbmfile="${hgbase}/.hg/bookmarks.current"
> >  branchfile="${hgbase}/.hg/branch"
> > +topicfile="${hgbase}/.hg/topic"
> >  rebasefile="${hgbase}/.hg/rebasestate"
> >  dirstatefile="${hgbase}/.hg/dirstate"
> >  mqstatusfile="${patchdir}/status" # currently applied patches
> > @@ -69,6 +70,13 @@ fi
> >  # If we still don't know the branch it's safe to assume default
> >  [[ -n ${r_branch} ]] || r_branch="default"
> >
> > +# Show topic if there is any (the UI for this experimental concept is 
> > not yet
> > +# final, but for a long time the convention has been to join the 
> > branch name
> > +# and the topic name by a colon)
> > +if [[ -r ${topicfile} ]] ; then
> > +    r_branch=${r_branch}:$(< ${topicfile})
> > +fi
> > +
> >  # The working dir has uncommitted-changes if the revision ends with a 
> > +
> >  if [[ $r_lrev[-1] == + ]] ; then
> >      hgchanges=1