[PETSC #18705] PETSc and Cygwin License (POSIX layer)

[Jed Brown]

On Thu 2008-12-04 16:58, Lisandro Dalcin wrote:
> On Thu, Dec 4, 2008 at 4:42 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> >
> >  Make is NOT the problem! (It is just one of several)
> 
> Indeed. However, at some time I'll try to make PETSc build with Scons.

Presumably you have some experience with SCons, but I think it's really
not such a good way to go.  It's pretty slow for large projects and the
caching design seems to generate inconsistent state somewhat regularly.
Also, big projects seem to always end up with a fork of SCons or abandon
it for alternatives.

I've been using CMake for my stuff (linking against PETSc and a few
other libs).  The syntax is pretty hideous for scripting, but the
declarative build definition is very nice.  Since it uses the native
build system, the IDE-using people on Windows would probably prefer it
as well.  It would be trivial (like an hour, plus some for tests) to
replace the current recursive make with CMake, replacing BuildSystem
would obviously require a bit of tedium, if it was even desirable.
BuildSystem is a very different beast from the "configuration" tools
that are out there since it also fills in as a package manager
(extremely nice since lots of optional dependencies have really painful
build systems).

In any case, having proper dependency analysis would be *really* cool, a
do-nothing rebuild of ParaView (includes VTK, >2M LOC in many
directories) takes 10 seconds so the usual PETSc few-file recompile
after 'hg pull -u' would be a 2-second affair.

Anyway, I'd suggest having a look at CMake before implementing an SCons
build.

Jed
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