Re: [gentoo-portage-dev] use* cleanup

[Marijn Schouten (hkBst)]

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Mike Frysinger wrote:
> On Wednesday 31 October 2007, Marijn Schouten (hkBst) wrote:
>> I hope this is just an artifact of the patch being a bit opaque. The
>> inconsistent indentation in the patch is a consequence of emacs bash mode
>> using a different indentation style than (I guess) vi(m). I'm sure even in
>> vi you can re-indent my code with one simple key-chord.
>
> no idea, i dont use vi ... but you're writing the patch which means you get to
> fix it ;)

Sure, I can do that.

>> The immediate motivation of my examining this code was a request on
>> #gentoo-dev-help by lack for something which I could with my new code
>> easily write like this:
>>
>> use_mime() {
>>     local WORD="$(_if $2 $2 $1)"
>>
>>     _use $1 "${WORD};"
>> }
>
> write where ?  in eclasses/ebuilds ?

yes

>>     local SUFFIX="$(_if $3 "=$3")"
>>     local WORD="$(_if $2 $2 $1)"
>
> local FOO=$(...)
> extraneous quoting makes eyes bleed
>
>> _if() {
>>     if $1; then echo $2; else echo $3; fi
>> }
>
> $1 && echo $2 || echo $3

Sure :)

>>     if hasq ${flag} ${USE} ; then
>> 	echo ${string_success}; return ${found}
>>     else
>> 	echo ${string_failure}; return $((!found))
>>     fi
>
> no point in cuddling those lines

Hmm, cuddling? I don't know what that means in this context.

>> What's not to like?
>
> when you've written it out, it does look much nicer ... but i'd like to
> understand the motivation behind it first ...

It seems the logical way to do it. Having a versatile function that checks use
flags and emits strings is very useful. Without it people will reimplement it
in a half-assed way time and time again in their ebuilds or eclasses. I've
done this myself. For example in dev-scheme/bigloo-3.0b_p2 I use:

./configure \
$(use java && echo "--jvm=yes --java=$(java-config --java)
- --javac=$(java-config --javac)") \
- --prefix=/usr \
# --bee=$(if use fullbee; then echo full; else echo partial; fi)

it would be a bit nicer if I could just write:

./configure \
$(_use java "--jvm=yes --java=$(java-config --java) --javac=$(java-config
- --javac)") \
- --prefix=/usr \
# --bee=$(_use fullbee full partial)

In gambit I used:

econf $(if use static; then echo --disable-shared; else echo --enable-shared;
fi) \

could become:

econf $(_use static --disable-shared --enable-shared) \

The example from
<http://www.gentoo.org/proj/en/devrel/handbook/handbook.xml?part=2&chap=1>

    if use gnutls ; then
        myconf="${myconf} --enable-ssl --with-ssl=gnutls"
    elif use ssl ; then
        myconf="${myconf} --enable-ssl --with-ssl=openssl"
    else
        myconf="${myconf} --disable-ssl"
    fi

    econf \
        # Other stuff
        ${myconf} \
        || die "configure failed"

could become:

    econf \
	# Other stuff
        $(_use gnutls "--enable-ssl --with-ssl=gnutls" \
		$(_use ssl "--enable-ssl --with-ssl=openssl" --disable-ssl)) \
	|| die "configure failed"

which may require some getting used to.

These are just a few small examples. I'm sure there are much better examples,
perhaps the use_mime thingy, but more importantly perhaps there is nothing
that you cannot do with the new code that you could do with the old.

Marijn

- --
Marijn Schouten (hkBst), Gentoo Lisp project
<http://www.gentoo.org/proj/en/lisp/>, #gentoo-lisp on FreeNode
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