Re: [RFC/PATCH] WIP: add deprecation & experimental process/interface

From: Junio C Hamano <gitster@pobox.com>
Date: May 29, 2017, 01:09 UTC
Message-ID: <xmqq4lw4a2pd.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <20170527111032.30897-1-avarab@gmail.com>

Ævar Arnfjörð Bjarmason  <avarab@gmail.com> writes:

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> diff --git a/GIT-VERSION-GEN b/GIT-VERSION-GEN
> index 4f94fc7574..c76bbedf86 100755
> --- a/GIT-VERSION-GEN
> +++ b/GIT-VERSION-GEN
> @@ -37,4 +37,5 @@ fi
>  test "$VN" = "$VC" || {
>  	echo >&2 "GIT_VERSION = $VN"
>  	echo "GIT_VERSION = $VN" >$GVF
> +	echo "GIT_VERSION_INT = $(echo $VN | sed -e 's/^\([0-9]*\)\.\([0-9]*\)\..*/\1\2/')" >>$GVF
>  }

Unlike Perl's v1.2.3.4 notation, this forces us worry when we go from v2.99.0 to v2.100.0 and eventually to v3.0, no?

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> +	} else if (1) {
> +		/*
> +		 * TODO: Instead of `if 1` we should check a
> +		 * core.version variable here.
> +		 *
> +		 * I.e. if set to core.version=2.13 the user is opting
> +		 * in to get deprecations set at dep_at right away,
> +		 * and also perhaps experimental features from a
> +		 * sister experimental() interface.
> +		 */

This essentially forces us to always read _some_ configuration. Some commands are meant to work outside repositories, so those who want to affect them needs to write core.version in their global configuration. Some low-level plumbing commands may want to do absolute minimum without configurablity.

I am not saying that it is absolutely a bad design decision to force us to read some configuration (yet); it's just that it is something that we have to keep in mind and always think about the ramifications of.

> +		die(_("Early bird deprecation error: %s"), message);
> +	}
> +}