Re: Update on distro bootstrapping with Guix

[Richard Stallman]

    > I suggest that, for shared libraries, the hash should disregard the
    > library's current version, and consider only the interface version.
    > That way, replacement of the shared library won't require any change
    > in the installed executable.

    I understand the motivation, but that would actually be contrary to the
    initial design goals, which enable the nifty features mentioned earlier.

I see what you mean -- but this is a high price to pay for those
benefits.  This suggests we look for a compromise solution that would
get most of those benefits while avoiding the price.

My previous suggestion is, in effect, one such compromise.  It is to
do the hashing as now for everything but shared libraries.  For them,
hash the interface version.  For many users, this compromise may be
advantageous.

However, by changing the shared library linking mechanism, it could be
possible to to get essentially all the benefit without the price.  The
idea is to create a way to specify, for each package, which library
version to use at run time.

The idea is that for each shared library interface version, record
which library versions are present, and have one that is selected.  By
default, every program that wants that interface version will get the
selected library version.  However, in the directory for a package
there can be file that gives a list of shared library names and
interface version numbers, specififying the library version to use for
that.

I think this gets the best of both worlds.  You will be able to update
shared libraries without reinstalling applications, and most of the
time everything will use the updated library, but you can make an
application use an older library version when you prefer.

What do you think?

-- 
Dr Richard Stallman
President, Free Software Foundation
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