Re: What to do when udpating a package ?

[zimoun <zimon.toutoune@gmail.com>]

On Fri, 15 May 2020 at 17:43, Edouard Klein <edk@beaver-labs.com> wrote:

> I could not find the link to the raw log, but having access to the
> "official" build status is a huge relief, as I can stop worrying that
> the build failure is my fault. This is exactly what I was looking for.
> Thank you !

I have cheated a bit because with this example, there is not raw -- I
do not know why.  But you get the principle. :-)


> >>   --> Is there a way to check the graph to make the edges as
> >>       sparse as possible (i.e. remove as many edges as possible without
> >>       changing the reachability) ? Would this be something we want ?
> >>       According to me it would because it would make the packages
> >>       definitions shorter and the computations on the graph faster, but I'm
> >>       not sure.
> >
> > What do you mean by "reachability"?
> > There is a new feature to "guix graph": '--path'.  You can find the
> > shortest path from one package to another, e.g.,
> >
> >   guix graph --path guix-jupyter python
> >
> > What do you mean by "the edges as sparse as possible"?
> >
> >
> So if A depends on B and C, and B also depends on C, which is preferable
> as far as explicit input declarations in the packages code go:
> --

(1)
> A->B;
> B->C;

(2)
> A->B;
> A->C;
> B->C;

If A depends on B *and* C, then (1) should not work.
Well, it depends on how A depends* on C and what C propagates.
If I understand correctly.

*build-time or runtime.


> The reachability (in the graph theoretical sense
> https://en.wikipedia.org/wiki/Reachability) is the same, but one graph
> has one edge less and is thus "minimal". If I understood Julien correctly he seems to think
> that the fully connected case is better (easier maintainability).

Well, does "guix graph --path" cover your expectation about reachability?
Because "guix graph --path" computes the shortest path -- graph theory
meaning -- from s to t.  So if the path is not empty, then t is
reachable from s.


All the best,
simon