[CMake] How to detect & set dependences when build-time(not when cmake)?

[持重 金]

Hello every one.


Recently, I try to rewrite a large project's building system by using cmake.
I meet a difficult point, how to detect & set dependences when build-time.

I have lot of this requirement, and currently I solve it with some terrible ways. I want some refined ways. For example:

    Using precompiled header file. 

        Cmake do not support pch directly and can not detect a header's dependences as a source file. 

        I can't set pch's dependences when cmake-time because it's changed frequently and it's dependences is tree structures.
        Currently, I create a assistant library-target, it have a cpp file only that includes precompiled header, and then add_custom_command depend it.
        So, once assistant library-target build, the precompiled header is recompiled. (How terrible it is.)

    Compile qrc file.
        If I scan qrc's dependences on cmake-time, and I remove some of file from qrc file after running cmake.Then I got an error, because qrc still depend it.
        So, currently I use "configure" command to copy qrc file in order to update qrc's dependences when cmake to check-build-system.

    Compile idl file.
        Just as previous requirement, idl's dependences is tree structures. In addition I write a script to scan dependences. How can I run this script on build-time.

        Currently, I have no ways.

In CMake 2.8's document I see that add_custom_command has an IMPLICIT_DEPENDS but I can't find any more data about it. And I have not found any where use it.