[Modules] pkg-config: libs, includes, cflags and dependancies

[Jones, W. <Wes...@nr...>]

Along the lines of Stenn's question, How are people supporting compiler
flags?  It seems hard to add and delete flags from an environment
variable list using straightforward modulefiles, and one probably 
does not want a global CFLAGS environment variable anyway.

So, I began to integrate the use of pkg-config into my use of modules.

If you are using the gnu tools and autoconfig with defined depenencies, 
you can just use the PKG_CONFIG_PATH to load different packages and
versions.

Otherwise, I also define some standard environment variables based on
the output from pkg-config.  I like to base the flags on an execution
of pkg-config, so that I can make modifications to $modroot/lib/$PKG.pc
without modification of the modulefiles.

Unfortunately, in my modulefiles, when I envoke modules to unload a 
package, the setenv (interpreted as an unsetenv when unloading) is 
still invoking the "pkg-config" command after the package has been 
removed from the PKG_CONFIG_PATH.  So, I have the ugly implementation
below.

If someone has a suggestion for better ways of doing this, or better
ways of including compiler flags in modules I'd like to hear them.

##
## modules $PKG $VERSION
##

module-whatis   "loads the $PKG software environment"

# for Tcl script use only
set     version         $VERSION
set     modroot         $ROOT/$PKG/\$version

prepend-path    PATH            \$modroot/bin
#AIX prepend-path    LIBPATH  \$modroot/lib
prepend-path    LD_LIBRARY_PATH  \$modroot/lib
prepend-path    MANPATH         \$modroot/man

prepend-path    PKG_CONFIG_PATH \$modroot/lib
if { ![is-loaded [module-info name]] && ![module-info mode load] ||
[module-info mode remove] } {
setenv          ${CAP_PKG}_LIBS       0
setenv          ${CAP_PKG}_CFLAGS     0
setenv          ${CAP_PKG}_INCLUDES   0
setenv          ${CAP_PKG}_FLIBS      0
setenv          ${CAP_PKG}_FFLAGS     0
} else {
setenv          ${CAP_PKG}_LIBS       [exec pkg-config --silence-errors
--libs $PKG]
setenv          ${CAP_PKG}_CFLAGS     [exec pkg-config --silence-errors
--cflags $PKG]
setenv          ${CAP_PKG}_INCLUDES   [exec pkg-config --silence-errors
--cflags-only-I $PKG]
setenv          ${CAP_PKG}_FLIBS      [exec pkg-config --silence-errors
--variable=FLIBS $PKG]
setenv          ${CAP_PKG}_FFLAGS     [exec pkg-config --silence-errors
--variable=FFLAGS $PKG]
}

---
Wesley Jones, Ph.D.                   
Senior Computational Scientist        Phone: 303-275-4070
National Renewable Energy Lab      wes...@nr...