[CFT+BRAINSTORM] One USE_ to rule them all

[René Ladan]

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On 04-02-2013 19:19, Baptiste Daroussin wrote:
> Hi,
> 
> I have some improvements to the ports tree to propose, and I'm
> looking for testers/opinions
> 
> First let me explain:
> 
> I want to introduce a new USE_FEATURES macro into the ports tree
> 
> The goal of this macros is to be able to standardize how we call
> all the USE_* things as well as creating some "load on demand" code
> for a corresponding feature.
> 
> What I expect in long term is to get a more readable bsd.port.mk &
> friends, meaning easier to maintain
> 
> I except some performance improvements given that make will have to
> parse less things.
> 
> I also expect less complexity if bsd.*.mk code.
> 
> What will have is all/most of the code corresponding to a
> USE_SOMETHING right now will endup in a Mk/features/something.mk
> which will be loaded only if the ports defines: USE_FEATURES=
> something
> 
> the loading is done at the very early stage of bsd.port.post.mk to
> allow one to load modify USE_FEATURES depending on some options
> etc.
> 
> each features/*.mk is itself protected by a variable to avoid multi
> loading of the same file
> 
> if a feature depends on another one the feature itself just have to
> ".include" the other one.
> 
This sounds like a good idea to me.

> As a proof of concept I made the following: USE_FEATURES=	gmake
> (with a compatibility for USE_GMAKE to allow migration) 
> USE_FEATURES=	iconv (with a compatibility for USE_ICONV to allow
> migration) USE_FEATURES=	motif (with no compatibility as I have
> switched all the USE_MOTIF ports to use it) USE_FEATURES=	fise
> (with no compatibility as I have switched all the USE_FUSE to use
> it) USE_FEATURES=	display (with no compatibilify as I have switched
> all the USE_DISPLAY to use it) USE_FEATURES=	pathfix (which is the
> equivalent of USE_GNOME= gnomehack without the need to loading the
> whole bsd.gnome.mk)
> 
> The very long term goal will be to switch as much code as possible
> to be turn into a feature (when it makes sens of course)
> 
Are you saying that some USE_BLAH=yes will stick around or do I
misunderstand?

Another question: for USE_BLAH=yes the logical transformation would be
USE_FEATURES=BLAH but what about USE_FOO=BLAH ? Would
USE_FEATURES=FOO/BLAH (possibly another separator) or
USE_FEATURES=BLAH be more sensible?

> The USE_FEATURES itself: 
> http://people.freebsd.org/~bapt/features.diff
> 
> The modified ports for the PoC: 
> http://people.freebsd.org/~bapt/features-chase.diff
> 
You could commit the header updates already if possible, which also
makes the patch more readable.

Regards,
René


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