[CMake] Run/build custom command/target only when "input" files change

[Richard Wackerbarth]

On Mar 8, 2011, at 5:10 AM, Mika.Rajala at patria.fi wrote:

> 
> foreach(in_file ${ARGN}) 
> 
> .... 
> 
> ADD_CUSTOM_COMMAND( 
>         OUTPUT ${IDL_OUTPUT_DIR}/${out_file}.h 
>                 ${IDL_OUTPUT_DIR}/${out_file}.tlb 
>         DEPENDS ${in_file} 
>         COMMAND(${MIDL_EXECUTABLE} ${in_file} <insert other args here> 
>         WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR} 
> ) 
> 
> .... 
> 
> endforeach() 

> Did i miss something? 
> 
> -mika 

How is "out_file" defined?
At the beginning of the second run, what files are in the {IDL_OUTPUT_DIR} directory?