[petsc-dev] circular dependencies SLEPc

[Jed Brown]

"Smith, Barry F." <bsmith at mcs.anl.gov> writes:

>> On Jun 26, 2019, at 1:53 PM, Jed Brown <jed at jedbrown.org> wrote:
>> 
>> "Smith, Barry F." <bsmith at mcs.anl.gov> writes:
>> 
>>>  It is still a PC, it may as part of its computation solve an eigenvalue problem but its use is as a PC, hence does not belong in SLEPc.
>> 
>> Fine; it does not belong in src/ksp/pc/.
>
>   Why not? From the code mangement point of view that is the perfect place for it. It just depends on an external package in the same way that PCHYPRE depends on an external library. Having it off in some other directory src/plugins would serve no purpose. Of course making sure it doesn't get compiled into -lpetsc may require a tweak to the make infrastructure. Make could, for example, skip plugin subdirectories for example.

I think it's confusing to have code that is part of libpetsc.so
alongside code that is not (e.g., won't be accessible to users unless
they also build SLEPc and link the plugin).

>   BTW: Matt's perverse use of SNES from DMPLEx could also be fixed to
>   work this way instead of the disgusting PetscObject casting used to
>   cancel the SNES object.

That code could be part of libpetscsnes.so.