[CMake] Auto-convert all IDL files in a tree?

[Alan W. Irwin]

On 2007-06-23 18:54-0400 Dave Wolfe wrote:

>>> I have a project with some (home-brewed) IDL files that I need to run
>>> a python script on to convert to CPP.  Some of these IDL files
>>> include other IDL files, which may, in turn, include *other* IDL
>>> files...
>
>
>> It appears from what you have said, that ...
>>                                     you need to deal with the
>> dependencies dynamically at build time rather than cmake time.
>
> Yes, that seems to be the case.
>
>> If you were willing to accept static idl dependencies then you could
>> use EXECUTE_PROCESS to run your python script to generate the cpp file
>> and determine a static list of idl dependencies at cmake time, and use
>> ADD_CUSTOM_COMMAND to regenerate the cpp file (if necessary) at build
>> time (i.e., make time) if any of the static list of dependencies has
>> been changed/edited (aside from changes to include commands).  Of
>> course, you could remove the cache file and rerun cmake to update the
>> list of static dependencies that are paid attention to in the
>> Makefile, but that takes human understanding of when the include
>> statements have changed so the procedure is subject to human error but
>> may be a compromise that reasonably satisfies your needs.
>
>
> Hmm.  Is there a way to 'fake out' CMake so it re-runs itself the next
> time a target is built?  Maybe make a build rule that touches the
> top-level CMakeLists.txt file, or some other file?  That wouldn't be a
> perfect solution, but it would be good enough, I think...
>

I don't know.

Here are two other possibilities to give you some food for thought.

(1) I have never done this myself, but I have heard on this list that for
     really intricate stuff it is nice to use a cmake -P script (presumably
     at build time as part of a custom command).  Anyhow, you should look at
     that possibility to see if it might answer your needs.

(2) You could just forget about all the dependency stuff and simply use a
     custom target (as opposed to a custom command) to _always_ regenerate
     the CPP file at build time regardless of whether there has been a change
     or not in the idl files.  That is certainly a safe procedure, but you
     will have to be the judge of whether it is acceptably efficient or not.

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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