On Sun, Apr 24, 2016 at 01:19:35PM +0200, Jan Nieuwenhuizen wrote: > Leo Famulari writes: > > I think we need to wrap gnome-tweak-tool's executable, which the > > python-build-system normally does automatically. AIUI, that's why all of > > the python-build-system packages don't require Python itself to be > > propagated. > > Sorry, I still don't understand. Can you explain why you want to remove > python2 from the propagated inputs?
Propagated-inputs are silently installed into the user's profile alongside the package that propagates them. In this case, installing gnome-tweak-tool would also install python2 into the user's profile. Propagation becomes attractive when the software provided by a package does not have a good mechanism for finding its dependencies. For example, some software may *only* be able to find a dependency by looking on PATH. Gnome-tweak-tool, as far as we know, has this limitation for python2. The problem with propagating inputs is that only one version of a given package may be installed into a user's profile. This is in contrast to "regular" inputs, which are not installed into a user's profile. Indeed, every package that you install into your profile could refer to a different version of, say, libfoo, by linking directly to the various libfoos' directories in the store. So, letting gnome-tweak-tool propagate python2 would prevent a Python programmer from choosing which version of python2 they want in their profile; they'd be forced to choose between gnome-tweak-tool or their desired python2. Does that make sense? > And also...say we wrap gnome-tweak-tool. If we remove python2 from the > propagated inputs, AIUI it python2 will not be installed and it even > could just be that python2 is not downloaded at all under /gnu. > > How is wrapping gnome-tweak-tool going to help if we fail to make sure > that python2 is present? Sorry for my ignorance. An alternative to propagated-inputs is to use a wrapper. Actually, all of our packages using the python-build-system are wrapped automatically [0]. The wrapper makes the dependent packages available in the run-time environment without polluting the user's profile, while introducing a reference to the dependencies into the store directory, which makes sure that the garbage collector works correctly. Does that make sense? Hopefully, I've got that all right — I'll be happy if somebody clarifies or corrects me! [0] If gnome-tweak-tool did not break convention by using the Autotools to build Python software, this discussion would not be happening ;)
