PETSC_DIR as a symlink

[Jed Brown]

On Thu, 26 Nov 2009 11:15:47 -0600 (CST), Satish Balay <balay at mcs.anl.gov> wrote:

> most of the other packages support multiple install modes. [for ex:
> mpich supports VPATH configure - which is equivalent to PETSC_ARCH].
> I think there is an issue with users having to remember/learn many
> types of installation methods for each package] - that pushes the idea
> that 'a single build model should work for all packages'..

Indeed, this is value in the more conventional model

$ mkdir build-descriptive-config
$ cd build-descriptive-config
$ ../configure --with-whatever --options # optionally with --prefix=/path/to/descriptive-config
$ make

I use this scheme, and will typically have at least two terminals in my
build tree, for instance at build-ompi-opt/src/fs/tests and
build-mpich-dbg/src/fs/tests.  Switching versions is similar difficulty
to changing PETSC_ARCH (I don't have to rebuild the example every time I
switch, but I do have to copy the command line to the other terminal).

With this model it is more tractable for the build system do proper
dependency analysis and only rebuild what is necessary (but at least
PETSc makefiles are easy to read).

Jed