Re: Foreign packages (formerly Re: [PATCH] gnu: Add ruby-nokogiri)

[Pjotr Prins]

On Sun, Feb 21, 2016 at 12:16:58PM +0100, Ricardo Wurmus wrote:
> > So any Ruby interpreter 2.2.x version will share the same gems. It is not
> > necessarily a problem because the Ruby world is built around this
> > assumption. But when I look at developer support and reproducibility I
> > don't like it much. You can have software running with different Ruby
> > interpreters under the hood - and you won't know it.
> 
> Do they really reference different variants of Ruby in the background?

Potentially: when you have a gem already installed and you update Ruby
to a newer version, you can run the old gem against the newer Ruby
provided it looks in the profile path for modules.

> The ruby-build-system adds the “ruby” package only to the build inputs.
> I don’t have different “ruby-*” packages in my store right now (after
> “guix gc”), so I cannot verify this myself.  I would be interested to
> know if references to the “ruby” package are actually retained when
> building, say, “ruby-nokogiri”.

Ruby is an input in the build system, right? After that...

> I haven’t thought enough about this to have an opinion about this.
> Generally, though, I dislike to use environment variables to point the
> interpreter to a prefix where all libraries can be found.  I think that
> it’s up to the libraries themselves to find their dependencies (like
> it’s done with RUNPATH).

You are right. The same holds for Guile, python, perl, R and Ruby at
this point. 

I think it would be OK to have a profile for every Ruby with libs. The
main problem here is that ruby interpreters can get mixed in with
existing (installed) modules.

I think Dave has pointed this out in the past. 

Pj.