[Plplot-devel] Splitting off libpltcl and greatly simplifying library linking options

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

I have just committed my changes to split out the pltcl library and I
also greatly simplified the linking flags.  The old model for linking flags
was to "throw in everything but the kitchen sink until the sucker worked".
The new model is to attempt to link just what is required and nothing more.

With the new model, applications only link libplplot (which is quite
convenient); libplplot only links libpltcl, the normal list of dynamic
drivers, and libg2c (the library required in Linux for fortran); and finally
libpltcl links the tcl, itcl, tk, itk, xwin, libtclmatrix, and the special
dynamic drivers.

These changes have been tested (my usual interactive and non-interactive
tests) in the plplot/tmp location and also in an arbitrary location with the
result installed with prefix = /usr/local/plplot.  I used the configure
options --with-double --enable-dyndrivers --enable-java --enable-gnome
--enable-ntk --enable-tkwin

I believe this new linking scheme should work for all modern Linux dynamic
loaders.  (Just for the record, my dynamic loader /lib/ld-2.2.5.so from
Debian woody is part of the libc6-2.2.5 package.) However, if I
recall correctly there was some evidence in the past that Joao's older
patched SuSe distribution had different linking requirements.  So Joao and
others, please test the latest CVS on your various Linux distributions
starting from a fresh checkout from CVS.  Note with the new model @LIBS@
(the combination of a zillion different linking flags) is no longer used,
but it is still defined in case we need it to support older dynamic loaders.

Maurice, I think if you followed what I did for libpltcl, you could also
easily split out the fortran interface from libplplot.

And similar remarks to Geoffrey about splitting out the java interface from
libplplot.

Other notes:

I believe the current scheme will work also for --disable-dyndrivers.  The
idea there is the special drivers get absorbed into libpltcl and the rest
get absorbed into libplplot.  But I haven't tested this at all.

I haven't yet thought much about the static library case.  For Linux
shouldn't we just drop that altogether?  Alternatively, we could make it a
non-default configuration item for Linux if there are still some important
Linux distributions that do not support shared libraries.

I haven't thought at all about our other platforms, but I will address that
issue once we are completely satisfied about the linking behaviour on Linux.

So please test the current CVS hard on as wide a variety of Linux platforms
as possible using --enable-dyndrivers.  If you want to try it without that
flag, I would also be interested in the results, but no guarantees it would
work!

Alan

email: ir...@be...
phone: 250-727-2902	FAX: 250-721-7715
snail-mail:
Dr. Alan W. Irwin
Department of Physics and Astronomy,
University of Victoria, P.O. Box 3055,
Victoria, British Columbia, Canada, V8W 3P6
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