Re: [gentoo-dev] RFC: GTK USE flag situation (gtk, gtk2, gtk3; relevant to bug #420493)

[Michał Górny]

Dnia 2014-02-12, o godz. 00:39:14
Alex Alexander <wired@g.o> napisał(a):

> Some developers choose to follow the Gnome team's highlights, while others
> choose to go their own way. The QA team would like to establish a guideline
> that solves this problem in the best way possible.

First of all, I think that the policy on a flag related to GTK+ should
be set by the GTK+ maintainer, that is the GNOME team, and not directly
by QA.

If people dislike the policy set by GNOME, they can appeal to QA, sure.
But IMO afterwards QA should either give their blessing to the current
GNOME policy or tell GNOME to change the policy, not step in front of
them with a 'higher instance override'.

> During our discussion, it was pointed out that keeping a generic USE="gtk" is
> sub-optimal. The non-straightforward nature of new toolkit versions makes
> transitioning from one to the other a slow, tedius process and we think that a
> non-versioned USE flag makes things even worse.

How does the flag exactly do that? I don't seem to get the point
in that paragraph.

> To achieve this, version 3 of gtk should always be enabled by USE="gtk3". At
> some point in the future, when gtk2 consumers reach zero, we will retire "gtk"
> for good. Then, if some day gtk4 comes around, we will be able to introduce
> support for it in the tree by simply adding USE="gtk4", without having to
> re-structure half the tree.

This goes exactly against the policy that is being established e.g. for
USE=ssl. If QA is really supposed to set a policy here, it should set
a generic policy for all those cases.

USE flags should represent *features*, not tools used to implement
them. If users want SSL support in an application, they want to set
USE=ssl and stop caring. Not look through all the USE flags in case
application used USE=openssl, USE=gnutls, USE=polarssl etc. for it.

Multiple USE flags make sense when there's support for multiple
toolkits that works and is maintained, and the user may reasonably want
to switch between them. But then, the extra USE flags for toolkit
switching should be introduced with keeping USE=ssl as the generic
on/off switch and the specific flags an optional implementation switch
for power users.

In the end, GTK+ is much the same. You want GTK+ GUI, you enable
USE=gtk. You need specific switching between 2 and 3, assuming it is
*reasonable and well supported*, you can use extra USE=gtk2 or
USE=gtk3. This generally works, and causes issues mostly to complainers
alike 'I dislike this, I want to be able to easily mask it all'.
I don't think there's a point messing up the general case for the sake
of complainers that will either end up enabling USE=gtk3 anyway at some
point or end up without a GUI.

That said, I'm all for killing most of USE=gtk, USE=wxwidgets, USE=qt*
occurrences with a generic USE=gui following the earlier principle.
If user installs an application and wants a GUI for it, shklee
shouldn't have to care whether it's GTK+, wxWidgets or Qt. Gentoo
should be a distribution friendly to all toolkits, people who collect
applications specific to a single toolkit belong in {,k,x}ubuntu.
Then, the special USE flags make sense for fine-picking one
of the toolkits when multiple are supported.

-- 
Best regards,
Michał Górny