Thanks, Lykurg for your fast reply! I did understand the part on macx and win32 platform specific codes.

But, what I mean is that how can I separate the C++ classes under single win32 platform?

e.g.
SimpleBuild (contains ClassA only)
AdvancedBuild (contains ClassA, ClassB, and ClassC)

I need to do different *pro file that uses different custom configuration to add files.

Qt Code: 
  1. win32:DEFINES += WIN32_ADVANCED
  2. win32:CONFIG += win32_Advanced
  3.  
  4. SUBDIRS += simple_build.pro
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Under SUBDIRS there are WIN32_ADVANCED flags to check whether the class is needed or not.
Then, under a controller class, there is a #ifdef win32_Advanced flag to include its header.

Hope this clarify my query.