Re: [PATCH v8 3/4] mergetool: Break setup_tool out into separate initialization function

[Johannes Sixt <j6t@kdbg.org>]

Am 28.12.20 um 05:54 schrieb Seth House:
> The tool-specific functions are sometimes needed in scope earlier than
> when run_merge_tool is called.

You should answer why this change is needed. "are sometimes needed in
scope earlier" cannot be true, else we would have a bug that is fixed by
this change. But this isn't a bug fix, is it?

It would be ok to say "We are going to add another thing that we will
need before run_merge_tool; this is a preparation" or something.

Which brings me to another point: I do not see that something is added
to initialize_merge_tool in a later patch. You are only replacing
setup_tool calls by initialize_merge_tool, which forwards to setup_tool.
Why do we need a new function?

> 
> Signed-off-by: Seth House <seth@eseth.com>
> ---
>  Documentation/git-mergetool--lib.txt | 4 ++++
>  git-difftool--helper.sh              | 2 ++
>  git-mergetool--lib.sh                | 7 ++++---
>  git-mergetool.sh                     | 2 ++
>  4 files changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/git-mergetool--lib.txt b/Documentation/git-mergetool--lib.txt
> index 4da9d24096..3e8f59ac0e 100644
> --- a/Documentation/git-mergetool--lib.txt
> +++ b/Documentation/git-mergetool--lib.txt
> @@ -38,6 +38,10 @@ get_merge_tool_cmd::
>  get_merge_tool_path::
>  	returns the custom path for a merge tool.
>  
> +initialize_merge_tool::
> +	bring merge tool specific functions into scope so they can be used or
> +	overridden.
> +
>  run_merge_tool::
>  	launches a merge tool given the tool name and a true/false
>  	flag to indicate whether a merge base is present.

[ swapped hunks for better sentence structure ]

> diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
> index 7225abd811..e059b3559e 100644
> --- a/git-mergetool--lib.sh
> +++ b/git-mergetool--lib.sh
> @@ -248,6 +248,10 @@ trust_exit_code () {
>  	fi
>  }
>
> +initialize_merge_tool () {
> +	# Bring tool-specific functions into scope
> +	setup_tool "$1" || return 1
> +}
>
>  # Entry point for running tools
>  run_merge_tool () {
> @@ -259,9 +263,6 @@ run_merge_tool () {
>  	merge_tool_path=$(get_merge_tool_path "$1") || exit
>  	base_present="$2"
>
> -	# Bring tool-specific functions into scope
> -	setup_tool "$1" || return 1
> -

Before this change, run_merge_tool would exit here when there was an
error during setup_tool. But...

> diff --git a/git-difftool--helper.sh b/git-difftool--helper.sh
> index 46af3e60b7..c47a6d4253 100755
> --- a/git-difftool--helper.sh
> +++ b/git-difftool--helper.sh
> @@ -61,6 +61,7 @@ launch_merge_tool () {
>  		export BASE
>  		eval $GIT_DIFFTOOL_EXTCMD '"$LOCAL"' '"$REMOTE"'
>  	else
> +		initialize_merge_tool "$merge_tool"
>  		run_merge_tool "$merge_tool"
>  	fi

... after the change we do not exit anymore. Does it matter?

Perhaps

		initialize_merge_tool "$merge_tool" &&
  		run_merge_tool "$merge_tool"

>  }
> @@ -79,6 +80,7 @@ if test -n "$GIT_DIFFTOOL_DIRDIFF"
>  then
>  	LOCAL="$1"
>  	REMOTE="$2"
> +	initialize_merge_tool "$merge_tool"
>  	run_merge_tool "$merge_tool" false
>  else
>  	# Launch the merge tool on each path provided by 'git diff'


> diff --git a/git-mergetool.sh b/git-mergetool.sh
> index e3c7d78d1d..929192d0f8 100755
> --- a/git-mergetool.sh
> +++ b/git-mergetool.sh
> @@ -334,6 +334,8 @@ merge_file () {
>  	checkout_staged_file 2 "$MERGED" "$LOCAL"
>  	checkout_staged_file 3 "$MERGED" "$REMOTE"
>  
> +	initialize_merge_tool "$merge_tool"
> +
>  	if test "$(
>  		git config --get --bool "mergetool.$merge_tool.automerge" ||
>  		git config --get --bool "mergetool.automerge" ||
>