[Plplot-devel] CMake progress with fortran, python, and CMake efficiency

[Alan W. I. <ir...@be...>]

Today, besides cheerleading from the side while Arjen, Werner, and Andrew
(Roach) sort out various windows issues, I have also made an important
efficiency improvement when there are small changes in the source tree, and
I have also been able to make some CMake improvements with both fortran
and python.

What I noticed while doing other work was that when one make command was
followed by another with little or no change in the source tree, way too
much work was being done.  With a lot of help from the CMake list I finally
tracked down the dependency issue, and now the second make takes literally
just a second of time on my 2.4GHz box which is a great improvement over
what was happening before.  I also notice that "make install" is also doing
a lot less work with this improvement.  So this should be a big help to
developers who typically want to make small changes in the source tree
followed by a fast make command that only updates what is necessary in the
build tree.  The improved speed of "make install" is nice as well.

For fortran 95 there is a bug in how CMake 2.4.3 parses fortran source files
when it looks for modules and include statements.  (It doesn't properly
ignore comments.) We have a somewhat ugly workaround in place for this first
CMake bug (replace "use" by "use_" in fortran source comments).  Thus,
Andrew Ross and I were happy to hear the CMake developers were actively
working on a fix for this bug.  However, that causes a potential problem
because there is also a second bug in how CMake 2.4.3 tracks fortran module
dependencies, and our old workaround for that second bug depended on the
first bug _not_ being fixed.  Today, I was able to change to a new
workaround for the second bug that is completely independent of the first
bug. Once I get deeper understanding of the source of the second bug, I will
submit a bug report to the CMake developers for their consideration, but
meanwhile the (new) workaround for the second bug is working fine and should
continue to work fine when the first bug is fixed.

The CMake improvement I made for python is the build tree examples now run
with ctest.  In CMake there is really easy syntax for configuring and
installing files with renames so it was a snap to implement this in a way
that clearly separated the build tree example tests for python from the
install tree example tests for python using one template file in the source
tree and two separate files in the build tree that are configured from that
template file. Currently our ABS _probably_ separates the two cases, but
both build and install locations are mentioned in one rather obfuscated
configuration file so it is difficult to be sure of that separation in all
circumstances.

Alan
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Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
package (plplot.org); the Yorick front-end to PLplot (yplot.sf.net); the
Loads of Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
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Linux-powered Science
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