Re: [PATCH v2 1/2] ref-filter: add worktree atom

[Nickolai Belakovski <nbelakovski@gmail.com>]

I think if we move to making this atom just store worktree path, that
needs to be implemented as a hashmap of refname->wtpath, which would
also solve this string_list issue, correct? Just making sure I'm not
missing something before I submit another patch.
On Tue, Nov 13, 2018 at 2:38 AM Junio C Hamano <gitster@pobox.com> wrote:
>
> Jeff King <peff@peff.net> writes:
>
> >> I wonder if "The worktree at /local/src/wt1 has this branch checked
> >> out" is something the user of %(worktree) atom, or a variant thereof
> >> e.g. "%(worktree:detailed)", may want to learn, but because that
> >> information is lost when this function returns, such an enhancement
> >> cannot be done without fixing this funciton.
> >
> > Hmm. I think for the purposes of this series we could jump straight to
> > converting %(worktree) to mean "the path of the worktree for which this
> > branch is HEAD, or the empty string otherwise".
> >
> > Then the caller from git-branch (or anybody wanting to emulate it) could
> > still do:
> >
> >   %(if)%(worktree)%(then)+ %(refname)%(end)
> >
> > As a bonus, the decision to use "+" becomes a lot easier. It is no
> > longer a part of the format language that we must promise forever, but
> > simply a porcelain decision by git-branch.
>
> Yeah, thanks for following through the thought process to the
> logical conclusion.  If a branch is multply checked out, which is a
> condition "git worktree" and "git checkout" ought to prevent from
> happening, we could leave the result unspecified but a non-empty
> string, or something like that.
>
> > file-global data-structure storing the worktree info once (in an ideal
> > world, it would be part of a "struct ref_format" that uses no global
> > variables, but that is not how the code is structured today).
>
> Yes, I agree that would be the ideal longer-term direction to move
> this code in.
>
> >> > +          } else if (!strcmp(name, "worktree")) {
> >> > +                  if (string_list_has_string(&atom->u.worktree_heads, ref->refname))
> >>
> >> I thought we were moving towards killing the use of string_list as a
> >> look-up table, as we do not want to see thoughtless copy&paste such
> >> a code from parts of the code that are not performance critical to a
> >> part.  Not very satisfying.
> >>
> >>      I think we can let this pass, and later add a wrapper around
> >>      hashmap that is meant to only be used to replace string-list
> >>      used for this exact purpose, i.e. key is a string, and there
> >>      is no need to iterate over the existing elements in any
> >>      sorted order.  Optionally, we can limit the look up to only
> >>      checking for existence, if it makes the code for the wrapper
> >>      simpler.
> >
> > This came up over in another thread yesterday, too. So yeah, perhaps we
> > should move on that (I am OK punting on it for this series and
> > converting it later, though).
>
> FWIW, I am OK punting and leaving, too.