[CFT+BRAINSTORM] One USE_ to rule them all

[Baptiste Daroussin]

On Mon, Feb 04, 2013 at 07:53:39PM +0100, René Ladan wrote:
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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?
> 

patch has been updated to be able to support the following:

USE_FEATURES=	foo:bla
that will 1/ load foo.mk, 2/ create a variable: FEATURE_foo= bla

So that you can do virtually any thing you want :)

regards,
Bapt
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