[CMake] delayed target

[Andrea Crotti]

On 02/22/2012 05:14 PM, Michael Hertling wrote:
> On 02/22/2012 05:02 PM, Andrea Crotti wrote:
>> Again I'm having some troubles with the different building stages:
>>
>> I would like to have a target that simply unzips all the files contained
>> in a directory,
>> which can be found with a simple globbing.
>>
>>    add_custom_target(unzip_all_eggs
>>      file(GLOB eggs RELATIVE ${EGG_BUILD_DIRECTORY}/*egg)
>>      COMMAND ${PYTHON_EXECUTABLE} ${UNZIP_SCRIPT} ${egg}
>>      )
>>
>>
>> The problem is that [...]
> ...FILE(GLOB ...) is a CMake command executed by CMake, whereas the
> custom target's COMMANDs are executed by the build tool at build
> time, so this approach fails from the first.
>
>> A possible solution is to make my UNZIP_SCRIPT smarter and just do the
>> globbing
>> itself, is there any other more CMake-like solution?
> ADD_CUSTOM_TARGET(unzip_all_eggs
>      ${CMAKE_COMMAND}
>          -DEGGDIR=${EGG_BUILD_DIRECTORY}
>          -P ${CMAKE_SOURCE_DIR}/unzip_all_eggs.cmake)
>
> # ${CMAKE_SOURCE_DIR}/unzip_all_eggs.cmake:
> SET(PYTHON_EXECUTABLE ...)
> SET(UNZIP_SCRIPT ...)
> FILE(GLOB eggs RELATIVE ${EGGDIR}/*egg)
> EXECUTE_PROCESS(
>      COMMAND ${PYTHON_EXECUTABLE} ${UNZIP_SCRIPT} ${eggs}
>      WORKING_DIRECTORY ...
> )
>
> You might want to provide an unzip_all_eggs.cmake.in template including
>
> SET(PYTHON_EXECUTABLE @PYTHON_EXECUTABLE@)
> SET(UNZIP_SCRIPT @UNZIP_SCRIPT@)
>
> use CONFIGURE_FILE(unzip_all_eggs.cmake.in unzip_all_eggs.cmake @ONLY)
> to generate the actual unzip_all_eggs.cmake after searching Python and
> your script, and specify -P ${CMAKE_BINARY_DIR}/unzip_all_eggs.cmake.
>

Thanks, this is really nice in general and I might use it in the future.
The problem is that in this specific case it doesn't buy me much and 
adds complexity, because
I would still have only one target unzipping all the eggs.

It would be nice to be able to generate N target 1 for each egg.

Anyway I think that just modifying the python unzip script to do the 
globbing is the
easier way to go in this case..