mpi

[Sean Farley]

Ryan Schmidt writes:

> On Sep 30, 2014, at 9:25 PM, Sean Farley wrote:
>> 
>>> That's not what variants are for. That's what subports are for.
>> 
>> Subports are trying to solve this but expose the implementation level
>> too far up. Only one solution should exist to depending on a
>> variant. Subports, unfortunately, put all the burden on the portfile
>> author and bloat the output of the list of ports.
>> 
>> $ port echo mpich*
>> mpich
>> mpich-clang
>> mpich-clang31
>> mpich-clang32
>> mpich-clang33
>> mpich-clang34
>> mpich-clang35
>> mpich-default
>> mpich-devel
>> mpich-devel-clang
>> mpich-devel-clang31
>> mpich-devel-clang32
>> mpich-devel-clang33
>> mpich-devel-clang34
>> mpich-devel-clang35
>> mpich-devel-default
>> mpich-devel-dragonegg31
>> mpich-devel-dragonegg32
>> mpich-devel-dragonegg33
>> mpich-devel-gcc43
>> mpich-devel-gcc44
>> mpich-devel-gcc45
>> mpich-devel-gcc46
>> mpich-devel-gcc47
>> mpich-devel-gcc48
>> mpich-devel-gcc49
>> mpich-devel-llvm
>> mpich-dragonegg31
>> mpich-dragonegg32
>> mpich-dragonegg33
>> mpich-gcc43
>> mpich-gcc44
>> mpich-gcc45
>> mpich-gcc46
>> mpich-gcc47
>> mpich-gcc48
>> mpich-gcc49
>> mpich-llvm
>> 
>> Why should this be exposed to the user? Imagine, now, if there were no
>> such thing as a variant. This would solve all the dependence issues on a
>> port's variant.
>
> I'm trying to explain that this is not what variants were made for.
>
> Variants are supposed to be for adding optional functionality, or choosing between options.

Variants create a new node in the dependency DAG. Subports create a new
node in the dependency DAG. There is no topological difference. The only
difference is in how they were implemented.

It is understandable to not want to implement the greater complexity.
Your proposal is to get rid of gcc for compiling C/C++. If that's the
direction MacPorts wants to go, then I'd request that it be uniform: no
port has any variant to change the C/C++ compilers.