[CMake] Multiple PROJECT() statements

[Alan W. Irwin]

On 2009-11-09 12:52-0800 Phil Smith wrote:

> I'm working with a CMakeLists.txt file I didn't create, so this may be a dumb question, but that won't stop me from asking it!
>
> We're using a System z cross-compiler called Dignus. I have it all working, but when we merged back into the SVN trunk, the PROJECT() statement became an issue.
>
> CMake is invoked thus:
> 	cmake -DCMAKE_TOOLCHAIN_FILE:string=".\zosport.cmake" -G"Unix Makefiles" .\
>
> zosport.cmake contains (among other things):
> 	SET(CMAKE_SYSTEM_NAME "IBM_ZOS")
>
> Through some MESSAGE() statements, I've convinced myself that zosport.cmake gets loaded by the PROJECT() statement. BUT I need to customize the PROJECT() statement based on the environment. What I have now is:
>
> 	project(vtk-core C)
> 	if(CMAKE_SYSTEM_NAME STREQUAL "IBM_ZOS")
> 	   project(vtk-core C ASM_DIGNUS)
> 	endif()
>
> This seems to work OK, but I wasn't sure if it was evil for some reason, or if there was a preferred approach.

I would suggest using enable_language instead, e.g.,:

project(vtk-core C)
   if(CMAKE_SYSTEM_NAME STREQUAL "IBM_ZOS")
     enable_language(ASM_DIGNUS)
   endif()

Even if running two project commands works in all cases, this
enable_language alternative is cleaner in the sense that it does not repeat
logic (such as enabling C).

Alan

P.S. There are no dumb questions.   :-)

Alan
__________________________
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 libLASi project (unifont.org/lasi); the Loads of
Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
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