On 16 February 2015 at 15:12, Kevin Kofler <kevin.kofler@xxxxxxxxx> wrote:
Christopher Meng wrote:
> Maintaining several version of the same library is not easy as you think,
> basically once a developer wants to install version X while then another
> people want to deploy things based on version Y, how to crack this nut?
> You can't just care about runtime.
Then you need to patch one or the other package to work with the same
version. Only if that is not possible, a compatibility library can be
considered. But we should always first try to make everything work with the
same version (if possible, the newer one).
The requirement to work with multiple versions of a package come up in the scientific/HPC community very frequently. Its not always about API compatibility, sometimes exact numerical reproduction is required which isn't preserved even between minor versions (i.e. an OS update). These environments usually (increasingly often) use the environment-modules package (ideally with relocatable packages) to select between libraries or incompatible subsystems. This is more often done by admins than explicit support from the OS packagers, but it *can* be done elegantly as part of the packaging process if there is a will.
Fedora already uses this - admittedly in rather limited ways;
# rpm -qf /etc/modulefiles/mpi/mpich-x86_64
mpich-3.1-4.fc21.x86_64
# rpm -qf /etc/modulefiles/mpi/openmpi-x86_64
openmpi-1.8.3-2.fc21.x86_64
Much more comprehensive environments can be built from the methodology.
Cheers, Martyn
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