[CMake] swig

[Brad King]

Peter Brown wrote:
> How can I add the dependencies manually to a swig target? I have:

Hmmm...it looks like there is no way to do it using the 
Modules/UseSWIG.cmake module that comes with CMake.  Look at the file 
and you'll see this custom command:

   ADD_CUSTOM_COMMAND(
     OUTPUT "${swig_generated_file_fullname}"
     COMMAND "${SWIG_EXECUTABLE}"
     ARGS "-${SWIG_MODULE_${name}_SWIG_LANGUAGE_FLAG}"
     ${swig_source_file_flags}
     ${CMAKE_SWIG_FLAGS}
     ${swig_special_flags}
     ${swig_extra_flags}
     ${swig_include_dirs}
     -o "${swig_generated_file_fullname}"
     "${swig_source_file_fullname}"
     MAIN_DEPENDENCY "${swig_source_file_fullname}"
     COMMENT "Swig source")

In order to add dependencies there needs to be a line like

DEPENDS ${swig_extra_depends}

after the MAIN_DEPENDENCY line.  Unfortunately it doesn't look like the 
interface to those SWIG macros was designed to enable extra dependencies 
so even if you add the line there is no easy way to specify the value of 
swig_extra_depends for each source file.  You can submit a feature 
request here:

http://www.cmake.org/Bug

but meanwhile you'll have to copy UseSWIG.cmake into your project and 
add dependency support yourself.  To get automatic dependencies you'll 
have to hack something like what I described here:

http://www.cmake.org/pipermail/cmake/2005-August/007102.html

> ADD_DEPENDENCIES(target
> file1.h
> file2.h
> ...
> )
> 
> If I choose as target "module_nameRUBY_wrap.cxx", cmake complains,
> that there is no such target. If I choose "module_name", it doesn't
> complain, but won't check for the dependencies.

ADD_DEPENDENCIES is only for top-level targets added with ADD_LIBRARY, 
ADD_EXECUTABLE, and ADD_CUSTOM_TARGET.  The next release of CMake 
includes documentation for ADD_DEPENDENCIES that makes this much more clear.

-Brad