Re: [gentoo-dev] GLEP: gentoo sync based unified deps proposal

[Michael Mol]

On Mon, Sep 17, 2012 at 9:48 AM, Ben de Groot <yngwin@g.o> wrote:
> On 17 September 2012 20:41, Ciaran McCreesh
> <ciaran.mccreesh@××××××××××.com> wrote:
>> On Mon, 17 Sep 2012 19:49:12 +0800
>> Ben de Groot <yngwin@g.o> wrote:
>>> Or, even easier and more straightforward: just keep using *DEPEND. The
>>> case hasn't been made yet why we need to change that in the first
>>> place.
>>
>> We're looking at something like eight *DEPEND variables in EAPI 6, with
>> considerable overlap between them all.
>
> And like now, in the great majority of cases, only two or three will be used.
> The enormous cost of moving to a different system (or the folly of using
> two systems in parallel) is not worth the slight benefit of a more cosmetic
> handling of the few cases where a few more *DEPEND variables would be
> needed and/or there is some overlap to be dealt with.

As someone who's been reading these threads, but hasn't actually
written any ebuilds from scratch, I'd like to offer my perspective as
a well-intentioned beginner:

On labels: The labels, to me, appeared largely more readable (and less
formidable a syntax to read and write as a human) than the foo? (
bar/baz ) syntax...until someone demonstrated a distinction between
depends and dependency types. I hadn't even noticed a distinction
between the two, until that point was raised.

While I like the labels (to me, they feel similar to Makefiles or C
switch statements), a clearer distinction between dependencies and
dependency types would be nice.

On unified DEPENDS vs *DEPEND: It seems to me that at a code level,
there's no real semantic difference. Since they both parse out
losslessly to the same abstract thing, you could serialize that
abstract thing back out into either format. Given most cases will be
simple, you could even serialize it away into something not
bash-based, if desired. All this means, to me, that the behavior of
the two under the hood is essentially irrelevant, and any bugs in
complex implementation could be caught with automated testing.

I personally favor a singular 'DEPENDS', because

1) I feel it would lead to better-organized documentation (I'm looking
for details about one var, rather than two or three vars--oh and then
there's the other N *DEPENDS I may not even have heard of yet), and

2) I worry less about accidental namespace pollution in my make.conf
file. Why do I worry about namespace pollution? Rather than using
profiles, I have around 40-50 USE flags divided by category into
varnames like SYS_USE_COMPRESION, and then I have a line that says
USE="${SYS_USE_CPU} ${SYS_USE_COMPRESSION} ${SYS_USE_DONOTWANT} # etc"
which coalesces it all. When I ran into a strange problem some time
back, someone assisting me initially suspected that my SYS_USE_* vars
might be conflicting with something internal to portage.

Again, this isn't coming from a seasoned developer, this is coming
from a well-intentioned beginner with very little time on his hands.
-- 
:wq