[gentoo-devhelp] Re: Re: LINGUAS vs LANGUAGES

[Steven J Long <slong@rathaus.eclipse.co.uk>]

Mike Frysinger wrote:

> On Tuesday 21 July 2009 06:13:25 Steven J Long wrote:
>> Nikos Chantziaras wrote:
>> > Thanks.  I ended up doing it this way, though with only one loop in
>> > src_install(), which seems to be a bit more efficient and shorter:
>> >
>> >
>> > LANGUAGES="de"
>> > for i in ${LANGUAGES}; do
>> > IUSE="${IUSE} linguas_${i}"
>> > done
>>
>> Just on a side-note (not saying it's how you want to do this one), this
>> is something that BASH arrays are nice for (saving another loop):
>> $ foo=(bar baz quux)
>> $ echo "prefixed: '${foo[*]/#/pfx_}'"
>> prefixed: 'pfx_bar pfx_baz pfx_quux'
> 
> printf would probably be better as it is typically a shell builtin and it
> doesnt require use of arrays/uncommon syntax.
> media-gfx/exiv2/exiv2-0.18.ebuild:
> IUSE_LINGUAS="de es fi fr pl ru sk"
> IUSE="${IUSE} $(printf 'linguas_%s ' ${IUSE_LINGUAS})"

Doh, forgot about printf. (We have alias print="printf '%s\n'" in our lib
code which comes in handy too.) Nice one.

The only issue with the above is that it requires a subshell; forking isn't
cheap (especially on Interix/cygwin/doze) and in general it's considered a
bit lame (at least amongst the ##bash old-timers that I bump heads with) to
need forking in BASH, though ofc not in SH, which is why it might not be
the best here, since the metadata generation phase is a restricted subset
of SH, leave alone BASH, at least aiui.

An example of BASH saving forking, would be where printf -v comes into play.
A more portable, though less flexible command in terms of allowed
characters is read from <<< [1]. Though that can be worked round, it's nice
not to have to; a shell that is progressing while still retaining excellent
portability is useful imo (so long as we don't get our knickers in a twist
about using new features, since we can set a required EAPI per-profile in
any case.)

[1] @freenode: /msg greybot <<<

Yes, I'm aware there are two versions of portability being discussed there.
I figured our readership can differentiate, and if not you can always
lead 'em gently by the hand to Massachusetts.. ;P
-- 
#friendly-coders -- We're friendly but we're not /that/ friendly ;-)