Re: [PATCH] list-packages: Display package usage count.

[Mark H Weaver <mhw@netris.org>]

Eric Bavier <ericbavier@gmail.com> writes:

> Ludovic Courtès writes:
>
>> Eric Bavier <ericbavier@gmail.com> skribis:
>>
>>> +  (define (users package)
>>> +    (let ((n (length (package-transitive-dependents
>>> +                      (find-packages-by-name* (package-name package)
>>> +                                              (package-version package))))))
>>
>> Why not just (package-transitive-dependents package)?
>
> Because that would not accurately count the "true" number of dependents.

Agreed, but what you wrote doesn't fully address the problem either.

If we modify 'gnu-make', that's also going to affect 'gnu-make-boot0' in
commencement.scm.  Since that one has a different name ("make-boot0"),
your logic won't catch it.

Similarly, if you modify 'gcc-4.7', that's also going to affect
'gcc-4.8' (different version) which affects 'gcc-boot0' (with a
different name and version).

So, it seems to me that we need a way to find all packages that
'inherit' from the package we're changing, transitively.  I'm not sure
off-hand if that information is preserved, but if not, we should
probably arrange to preserve it somehow.

      Mark