Re: [PATCH 00/14] Make git-pull a builtin

From: Junio C Hamano <gitster@pobox.com>
Date: May 18, 2015, 19:21 UTC
Message-ID: <xmqqh9r9bsji.fsf@gitster.dls.corp.google.com>
In-Reply-To: <1431961571-20370-1-git-send-email-pyokagan@gmail.com>

Paul Tan <pyokagan@gmail.com> writes:

> This series rewrites git-pull.sh into a C builtin, thus improving its
> performance and portability. It is part of my GSoC project to rewrite git-pull
> and git-am into builtins[2].

Earlier you were worried about 'git pull' being used in many tests for the purpose of testing other parts of the system and not testing 'pull' itself. For a program as complex as 'git pull', you may want to take the 'competing implementations' approach.

(1) write an empty cmd_pull() that relaunches "git pull" scripted
    porcelain from the $GIT_EXEC_PATH with given parameters, and
    wire all the necessary bits to git.c.

(2) enhance cmd_pull() a bit by bit, but keep something like this

	if (getenv(GIT_USE_BUILTIN_PULL)) {
        	/* original run_command("git-pull.sh") code */
                exit $?
	}

        ... your "C" version ...

(3) add "GIT_USE_BUILTIN_PULL=Yes; export GIT_USE_BUILTIN_PULL" at
    the beginning of "t55??" test scripts (but not others that rely
    on working pull and that are not interested in catching bugs in
    pull).

(4) once cmd_pull() becomes fully operational, drop (3) and also the
    conditional one you added in (2), and retire the environment
    variable.  Retire the git-pull.sh script to contrib/examples/
    boneyard.

That way, you will always have a reference you can use throughout the development.

Just a suggestion, not a requirement.