c++ - __FILE__ macro manipulation handling at compile time

Question

One of the issues I have had in porting some stuff from Solaris to Linux is that the Solaris compiler expands the macro __FILE__ during preprocessing to the file name (e.g. MyFile.cpp) whereas gcc on Linux expandeds out to the full path (e.g. /home/user/MyFile.cpp). This can be reasonably easily resolved using basename() but....if you're using it a lot, then all those calls to basename() have got to add up, right?

Here's the question. Is there a way using templates and static metaprogramming, to run basename() or similar at compile time? Since __FILE__ is constant and known at compile time this might make it easier. What do you think? Can it be done?

Answer 1

In projects using CMake to drive the build process, you can use a macro like this to implement a portable version that works on any compiler or platform. Though personally I pity the fool who must use something other than gcc... :)

# Helper function to add preprocesor definition of FILE_BASENAME
# to pass the filename without directory path for debugging use.
#
# Note that in header files this is not consistent with
# __FILE__ and __LINE__ since FILE_BASENAME will be the
# compilation unit source file name (.c/.cpp).
#
# Example:
#
#   define_file_basename_for_sources(my_target)
#
# Will add -DFILE_BASENAME="filename" for each source file depended on
# by my_target, where filename is the name of the file.
#
function(define_file_basename_for_sources targetname)
    get_target_property(source_files "${targetname}" SOURCES)
    foreach(sourcefile ${source_files})
        # Add the FILE_BASENAME=filename compile definition to the list.
        get_filename_component(basename "${sourcefile}" NAME)
        # Set the updated compile definitions on the source file.
        set_property(
            SOURCE "${sourcefile}" APPEND
            PROPERTY COMPILE_DEFINITIONS "FILE_BASENAME="${basename}"")
    endforeach()
endfunction()

Then to use the macro, just call it with the name of the CMake target:

define_file_basename_for_sources(myapplication)