Andreas Heiduk <asheiduk@xxxxxxxxx> writes:
> A specific `--setup` step in `git filter-branch` makes it much easier
> to define the initial values of variables used in the real filters.
> Also sourcing/defining utility functions here instead of
> `--env-filter` improves performance and minimizes clogging the output
> in case of errors.
>
> Signed-off-by: Andreas Heiduk <asheiduk@xxxxxxxxx>
> ---
I was placed on To: line, but I do not have a strong opinion on this
change, either for or against.
"filter-branch" program itself may probably already be hard to port
to C, but I need to point out that this makes it even harder than it
currently is [*1*], and it is likely that it has to stay implemented
in shell forever, though. I do not mind that future myself, but
those on platforms with weaker implementation of shells might.
[Footnote]
*1* The issue is *not* that these individual filter commands expect
<command> written as a shell scriptlet; it is that these
scriptlets expect to be evaled inside a single shell process,
making an update to a shell variable in one command visible to
the next command that runs.
> Documentation/git-filter-branch.txt | 16 +++++++++++-----
> git-filter-branch.sh | 18 +++++++++++++-----
> 2 files changed, 24 insertions(+), 10 deletions(-)
>
> diff --git a/Documentation/git-filter-branch.txt b/Documentation/git-filter-branch.txt
> index 6e4bb0220..45c849d8c 100644
> --- a/Documentation/git-filter-branch.txt
> +++ b/Documentation/git-filter-branch.txt
> @@ -8,11 +8,11 @@ git-filter-branch - Rewrite branches
> SYNOPSIS
> --------
> [verse]
> -'git filter-branch' [--env-filter <command>] [--tree-filter <command>]
> - [--index-filter <command>] [--parent-filter <command>]
> - [--msg-filter <command>] [--commit-filter <command>]
> - [--tag-name-filter <command>] [--subdirectory-filter <directory>]
> - [--prune-empty]
> +'git filter-branch' [--setup <command>] [--env-filter <command>]
> + [--tree-filter <command>] [--index-filter <command>]
> + [--parent-filter <command>] [--msg-filter <command>]
> + [--commit-filter <command>] [--tag-name-filter <command>]
> + [--subdirectory-filter <directory>] [--prune-empty]
> [--original <namespace>] [-d <directory>] [-f | --force]
> [--] [<rev-list options>...]
>
> @@ -82,6 +82,12 @@ multiple commits.
> OPTIONS
> -------
>
> +--setup <command>::
> + This is not a real filter executed for each commit but a one
> + time setup just before the loop. Therefore no commit-specific
> + variables are defined yet. Functions or variables defined here
> + can be used or modified in the following filter steps.
> +
> --env-filter <command>::
> This filter may be used if you only need to modify the environment
> in which the commit will be performed. Specifically, you might
> diff --git a/git-filter-branch.sh b/git-filter-branch.sh
> index aafaf708d..2758ae5eb 100755
> --- a/git-filter-branch.sh
> +++ b/git-filter-branch.sh
> @@ -81,11 +81,12 @@ set_ident () {
> finish_ident COMMITTER
> }
>
> -USAGE="[--env-filter <command>] [--tree-filter <command>]
> - [--index-filter <command>] [--parent-filter <command>]
> - [--msg-filter <command>] [--commit-filter <command>]
> - [--tag-name-filter <command>] [--subdirectory-filter <directory>]
> - [--original <namespace>] [-d <directory>] [-f | --force]
> +USAGE="[--setup <command>] [--env-filter <command>]
> + [--tree-filter <command>] [--index-filter <command>]
> + [--parent-filter <command>] [--msg-filter <command>]
> + [--commit-filter <command>] [--tag-name-filter <command>]
> + [--subdirectory-filter <directory>] [--original <namespace>]
> + [-d <directory>] [-f | --force]
> [<rev-list options>...]"
>
> OPTIONS_SPEC=
> @@ -96,6 +97,7 @@ if [ "$(is_bare_repository)" = false ]; then
> fi
>
> tempdir=.git-rewrite
> +filter_setup=
> filter_env=
> filter_tree=
> filter_index=
> @@ -148,6 +150,9 @@ do
> -d)
> tempdir="$OPTARG"
> ;;
> + --setup)
> + filter_setup="$OPTARG"
> + ;;
> --env-filter)
> filter_env="$OPTARG"
> ;;
> @@ -317,6 +322,9 @@ else
> need_index=
> fi
>
> +eval "$filter_setup" < /dev/null ||
> + die "filter setup failed: $filter_setup"
> +
> while read commit parents; do
> git_filter_branch__commit_count=$(($git_filter_branch__commit_count+1))