From mboxrd@z Thu Jan  1 00:00:00 1970
From: Junio C Hamano <gitster@pobox.com>
Subject: Re: A note on modern git plus ancient meld ("wrong number of
 arguments")
Date: Fri, 10 Feb 2012 13:28:55 -0800
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References: <20120209191742.GA20703@unpythonic.net>
 <CAJDDKr58LV9EDJZP+3S0YfyTOXFgJWD6nm=AiA19MkyBF-wb_g@mail.gmail.com>
 <20120210082106.GA7871@burratino>
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Cc: David Aguilar <davvid@gmail.com>,
	Jeff Epler <jepler@unpythonic.net>, git@vger.kernel.org,
	Sebastian Schuberth <sschuberth@gmail.com>,
	Charles Bailey <charles@hashpling.org>
To: Jonathan Nieder <jrnieder@gmail.com>
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In-Reply-To: <20120210082106.GA7871@burratino> (Jonathan Nieder's message of
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Jonathan Nieder <jrnieder@gmail.com> writes:

> Just parse version numbers instead.  We can detect the version number
> by running "meld --version" and postprocessing it.

Hmm. I am debating myself if it may be more efficient, less error prone
and simpler for the users if we gave them "mergetool.meld.useOutput"
configuration option to tweak.

When an older meld fails when given --output for real (not with the dry
run current code tries with --help), can we sanely detect that particular
failure?  If we can do so, another possibility may be to do something like
this:

merge_cmd () {
	meld_has_output_option=$(git config --bool mergetool.meld.useOutput)
	case "$meld_has_output_option" in
        false)
		... do the non-output thing ...
		;;
	true)
		"$merge_tool_path" --output "$MERGED" "$LOCAL" "$BASE" "$REMOTE"
		;;
	*)
		"$merge_tool_path" --output "$MERGED" "$LOCAL" "$BASE" "$REMOTE"
		if it failed due to missing --output support?
		then
			meld_has_output_option=no
                        git config mergetool.meld.useOutput false
			merge_cmd
		fi
                ;;
	esac
}