On Wed, Jun 10, 2015 at 10:44 PM, Junio C Hamano <gitster@xxxxxxxxx> wrote:
> Paul Tan <pyokagan@xxxxxxxxx> writes:
>
>>> Hmph, it is somewhat surprising that we do not have such a helper
>>> already. Wouldn't we need this logic to implement $branch@{upstream}
>>> syntax?
>>
>> Right, the @{upstream} syntax is implemented by branch_get_upstream()
>> in remote.c. It, however, does not check to see if the branch's remote
>> matches what is provided on the command-line, so we still have to
>> implement this check ourselves, which means this helper function is
>> still required.
>>
>> I guess we could still use branch_get_upstream() in this function though.
>
> It is entirely expected that existing function may not do exactly
> what the new caller you introduce might want to do, or may do more
> than what it wants. That is where refactoring of existing code
> comes in.
>
> It somewhat feels strange that you have to write more than "shim"
> code to glue existing helpers and API functions together to
> re-implement what a scripted Porcelain is already doing, though.
> It can't be that git-pull.sh implements this logic as shell script,
> and it must be asking existing code in Git to do what the callers
> you added for this function would want to do, right?
Not git-pull.sh, but get_remote_merge_branch() git-parse-remote.sh.
The shell code that get_upstream_branch() in this patch implements is:
0|1)
origin="$1"
default=$(get_default_remote)
test -z "$origin" && origin=$default
curr_branch=$(git symbolic-ref -q HEAD) &&
[ "$origin" = "$default" ] &&
^ This here is where it checks to see if the branch's configured
remote matches the remote provided on the command line.
echo $(git for-each-ref --format='%(upstream)' $curr_branch)
;;
^ While here it calls git to get the upstream branch, which is
implemented by branch_get_upstream() on the C side.
So yes, we can use branch_get_upstream(), but we still need to
implement some code on top.
Just to add on, the shell code that get_tracking_branch() in this
patch implements is:
*)
repo=$1
shift
ref=$1
# FIXME: It should return the tracking branch
# Currently only works with the default mapping
case "$ref" in
+*)
ref=$(expr "z$ref" : 'z+\(.*\)')
;;
esac
expr "z$ref" : 'z.*:' >/dev/null || ref="${ref}:"
remote=$(expr "z$ref" : 'z\([^:]*\):')
case "$remote" in
'' | HEAD ) remote=HEAD ;;
heads/*) remote=${remote#heads/} ;;
refs/heads/*) remote=${remote#refs/heads/} ;;
refs/* | tags/* | remotes/* ) remote=
esac
[ -n "$remote" ] && case "$repo" in
.)
echo "refs/heads/$remote"
;;
*)
echo "refs/remotes/$repo/$remote"
;;
esac
so it's more or less a direct translation of the shell script, and we
can be sure it will have the same behavior. I'm definitely in favor of
switching this to use remote_find_tracking(), the question is whether
we want to do it in this patch or in a future patch on top.
Thanks,
Paul
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