Re: Package transformations

[Ricardo Wurmus]

Ludovic Courtès <address@hidden> writes:

> I’ve pushed my “train hacks”, which are a continuation of refactoring
> work I had done in December (ca. 64ec0e2):
>
>   • ‘guix build’ has a new ‘--with-input’ option to rewrite the
>     dependency graph so you can run:
>
>       guix build guix --with-input=guile=guile-next
>
>     and guess what it does.  :-)
>
>     However, it only works for explicit inputs.

What does it mean that it only works for *explicit* inputs?  Does this
mean that default inputs added by the build system (e.g. GCC) cannot be
replaced?

Looking at the code it seems that it is operating on labels.  In the
past I have found that labels for the same package object are not always
identical.  For example “htseq” in “bioinformatics.scm” names uses the
label “python-numpy” for the package object named “python2-numpy”.  If I
used “--with-input=python2-numpy=my/python2-numpy” it would skip the
input labelled “python-numpy” (but change others in the graph with the
label “python2-numpy”) even though the package object is the same.

Is my understanding correct?  If so, should we instead attempt to match
on the package name of the package object rather than the label?  Or
should we be a little more careful with label names now that they are
also used outside of build phases?

I really like this additional feature!  Thanks!

~~ Ricardo