setup and 'provides:'

[Ken Brown]

On 10/8/2018 4:04 PM, Achim Gratz wrote:
> Ken Brown writes:
>> I created a test repo with packages A, B, and C.  I made A require foo (not a
>> package), and I made B and C provide foo.  The attached script does all this
>> [**].  I then ran setup and selected A for installation.
> 
> That really only makes sense if several packages provide the same
> feature(s).

Right.  I gave a potential example elsewhere in this thread, in which the 
feature emacs-bin is provided by the packages emacs, emacs-X11, emacs-lucid, and 
emacs-w32.  Fedora does something like this, except that it calls the feature 
emacs(bin).

>>  So we'd need to bolt on a feature space in setup as well.

I'm not sure what you mean by this.  setup doesn't need to know whether a 
requirement is a feature or a package.  It simply passes the dependencies (and 
the provides) to libsolv, which handles them just fine.

The only thing that I thought wasn't working right is libsolv's behavior when 
more than one package provides a certain feature and libsolv has to choose one 
for installation.  But I realize now that libsolv just doesn't do what I 
expected, and some non-trivial work on setup would be required in order to get 
the behavior I was expecting.  See my other messages in this thread.

Ken