Re: [PATCH 1/4] git-sh-i18n--envsubst: our own envsubst(1) for eval_gettext()

[Junio C Hamano <gitster@pobox.com>]

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

> Add a git-sh-i18n--envsubst program which is a stripped-down version
> of the GNU envsubst(1) program that comes with GNU gettext for use in
> the eval_gettext() fallback

Ok up to this point.

> ... instead of using a clever (but broken)
> printf + eval + printf trick.
>
> In a previous incarnation of the gettext series I implemented the
> eval_gettext() fallback like this:
> ...
> This was clever, but ...
> ... 
> To work around this, and to improve our variable expansion behavior
> (eval has security issues) I've imported a stripped-down version of
> gettext's envsubst(1) program.

I do not think the lengthy history of failed experiments above is worth
explaining. If you really want to say something to justify a new helper, I
think it is sufficient to just explain that it is unsolvable in shell. I
tried that in the first 9-line paragraph in:

  http://thread.gmane.org/gmane.comp.version-control.git/170703/focus=170770

In other words, "we tried X that didn't work and we tried Y that didn't
either, we cannot think of any better solution, so we are doing something
else" is not a good justificiation for doing that "something else".

"Anything based on shell is an unpractical solution for this and that
reasons, so we use this instead" explains that the earlier failures were
not because we did not try hard enough.  Unlike "tried X and Y but didn't
work", dismissing "anything based on shell" as a whole class with clear
explanation why it would not work would prevent people from pursuing that
dead-end approach.  It also avoids giving quibbling people an excuse to
argue against importing envsubst implementation saying "you didn't try
hard enough".

> With it eval_gettext() is implemented
> like this:
> ...
> Reported-by: Johannes Sixt <j.sixt@viscovery.net>
> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>

Ok.

> diff --git a/Documentation/git-sh-i18n--envsubst.txt b/Documentation/git-sh-i18n--envsubst.txt
> new file mode 100644
> index 0000000..e146a2c
> --- /dev/null
> +++ b/Documentation/git-sh-i18n--envsubst.txt
> @@ -0,0 +1,36 @@
> ...
> +Author
> +------
> +Written by Ævar Arnfjörð Bjarmason <avarab@gmail.com>
> +
> +Documentation
> +--------------
> +Documentation by Ævar Arnfjörð Bjarmason and the git-list
> +<git@vger.kernel.org>.

I do not think we do these individual credits these days in the doc.