[CMake] Forcibly run 'moc' on Qt files that are NOT part of the build

[Michael Jackson]

In an effort to speed up the build of a project that uses Qt (and moc) I tried an alternate approach with the moc files. Normally I use the basic idea of gathering the headers that need to be "moc'ed" and feed those to moc with this type of CMake Code:

QT4_WRAP_CPP( FilterWidgets_Generated_MOC_SRCS ${QFilterWidget_HDRS} ${FilterWidget_GEN_HDRS}) 

The in the Add_Executable(...) call include the ${FilterWidgets_Generated_MOC_SRCS} variable to the list of sources. In my project I have at least 30 auto-generated files which all get moc'ed. That gives me an additional 60 compiled files. So I tried the idea of #include "moc_[some_file.cxx]" in each of the auto-generated .cpp files for each Widget. This would cut the number of files compiled in half. The issue is that since they are being #include'ed in the .cpp files then they do NOT need to be compiled themselves so I took the ${FilterWidgets_Generated_MOC_SRCS} out of the list of sources in the add_executable() call. What happened is that CMake did NOT run moc on those headers because there were now NOT included in the build.

 So for that version of the cmake code I have something like this:

QT4_WRAP_CPP( FilterWidgets_Generated_MOC_SRCS ${FilterWidget_GEN_HDRS}) 
QT4_WRAP_CPP( FilterWidgets_MOC_SRCS ${QFilterWidget_HDRS} )

Is there a way to forcibly run the moc step even if the resulting source files are NOT directly included in the add_executable? Custom_Command? Add_Depends?

Thanks
___________________________________________________________
Mike Jackson                    Principal Software Engineer
BlueQuartz Software                            Dayton, Ohio
mike.jackson at bluequartz.net              www.bluequartz.net