Re: Is multiple-layers of alternatives a good thing to users?
- Date: Sun, 3 Feb 2019 21:34:08 +0000
- From: Ian Jackson <ijackson@xxxxxxxxxxxxxxxxxxxxxx>
- Subject: Re: Is multiple-layers of alternatives a good thing to users?
Mo Zhou writes ("Is multiple-layers of alternatives a good thing to users?"):
> A user suggested that the 6 variants of BLIS should be
> co-installable. However, making them co-installable would result in
> multiple layers of alternatives in the update-alternatives system and
> will possibly confuse users, as discussed in . I wrote this mail
> in case anyone has a better solution so we will have a chance to fix.
> Tacking the three 32-bit variants as examples, we will have the
> following alternative chain if the 3 variants were made co-installable:
> Package: libblis2-openmp, Provides: libblis.so.2
> Package: libblis2-pthread, Provides: libblis.so.2
> Package: libblis2-serial, Provides: libblis.so.2
> Package: libblis2 (meta), Provides: libblas.so.3, Depends: libblis.so.2,
> Package: python3-numpy, Depends: libblas.so.3
> numpy asks for libblas.so.3
> -> libblas.so.3 is an alternative pointing to libblis2
> -> libblis.so.2 is an alternative pointing to any one of the three variants
In general coinstallability is a good thing.
I don't understand why the multiple levels of alternatives are
inevitable. Why could each of the variants not provide both an
alternative option for libblas.so.3, and separately one for
This would mean that the user could choose a different library for
"programs which wanted BLAS" and "programs which wanted BLIS" but I
don't think that is a problem ?
(Getting there from here is left as an exercise to the reader...)
> Such layout not only makes the packaging more difficult to maintain, but
> also makes it harder for the user to understand what BLAS backend is
> actually invoked.
I agree that multiple layers of alternatives indirection is
undesirable. But I think these libraries can be made coinstallable
Ian Jackson <ijackson@xxxxxxxxxxxxxxxxxxxxxx> These opinions are my own.
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