Gentoo Archives: gentoo-dev

From: Brian Harring <ferringb@×××××.com>
To: Alistair Bush <ali_bush@g.o>
Cc: gentoo-dev@l.g.o, gentoo-council@l.g.o
Subject: [gentoo-dev] Re: [gentoo-council] pkg_pretend USE validation and VALID_USE alternative
Date: Wed, 31 Mar 2010 10:59:51
Message-Id: 20100331105738.GE11663@hrair
Note I inadvertantly cross posted, I was intending on cc'ing 

As such one final cc to that ml to end this subthread while pulling 
this back to -dev.

On Wed, Mar 31, 2010 at 11:16:22PM +1300, Alistair Bush wrote:
> > Hola all- > > > > Comments desired; assuming no significant blowback, I'll be pushing > > this to the council level since eapi4 is annoying feature locked right > > I think this solution is far better, until someone smarter than me tells me > otherwise. > > Don't know whether I like the VALID_USE var name, so please at least think > about something a little better if you can ;). ( I like green, but not too > green if you know what I mean ) > > Will we still have to define the use flags in IUSE?
Yes, although if folks have a better proposal that incorporates VALID_USE into IUSE I'm definitely open to it- the original proposal for VALID_USE tried to inline it into IUSE, but it got ugly (hence it mutating it this form). The problem w/ trying to reuse IUSE is the following (sorry, I like lists of assertions)- *) IUSE currently serves as a list of valid USE flags, just that. No repeat specification of a flag (which means the dev in question is unlikely to typo a flag). *) having a single specified list of valid use flags is the basis for doing validation of use flags used in all other metadata. In other words, that list of valid use flags *really* needs to go out of it's way to make human error hard. *) VALID_USE is a set of assertions on the allowed state of USE; IUSE is just a list of flags. Intermixing the two in a way that is still readable is really ugly *) given a library that has optional perl and python bindings (which can be toggled freely, they're standalone flags) I've nfc how one would sanely specify that w/in IUSE while adding VALID_USE semantics. Possibly, you could include use conditionals into IUSE, and treat the () contents as assertions- but that makes adding xor in hard, is rather ugly/hard on the eyes, and violates the DRY (Don't Repeat Yourself) principle from above. Definitely open to counterproposals that address those concerns however...
> I'm guessing we can't use IUSE to store this information because of the whole > glep-55 thing.
glep-55 is unrelated to this as far as I can tell- if you think otherwise please clarify. Thanks ~harring