Am Mittwoch, 26. Januar 2011 schrieb kfj:
> Hi all!
>
> I'm still struggling with cmake for hsi/hpi, and I just can't get my
> head round it's strange ways, and what online documentation there is I
> don't find helpful either. So maybe someone can help me with this
> simple problem:
>
> I have a C++ header file zz.h in my source directory
>
> I want this preprocessed by the C preprocessor into a file zz.i in the
> target directory
>
> This is a simple operation, and cmake even generates i-files as
> default targets in C++ projects. So if I have a simple CMakeLists.txt
> going like
>
> add_executable(xx xx.cpp)
>
> (really only this one line!) and xx.cpp is also very simple:
>
> #define mac "MACRO"
> int main ( int argc , char * argv[] )
> {
> char * str = mac ;
> }
>
> if i now run
>
> cmake .
> make xx.i
>
> I get this output:
>
> Preprocessing CXX source to CMakeFiles/xx.dir/xx.i
>
> lo and behold, CMakeFiles/xx.dir/xx.i is the C-preprocessed file. I
> didn't need to specify anything in the CMakeLists.txt, cmake knows
> perfectly well how to invoke the C/C++ preprocessor and make an i-file
> from a .cpp file. My question is: how can I get it to uses this
> capability on my source file zz.h to get zz.i in the target directory?
> So far the answer was to run a custom command, with differentiation
> between MSVC and gcc, probably use of a cmake command file - T. Modes
> has managed to coerce cmake into doing what's needed for hsi/hpi with
> a good dozen lines of code, but I have the feeling this is not at all
> needed - and the current code is so obscure that I'm not at all happy
> with it, because it's really such a standard task that in a classic
> makefile it'd be there by default, like .i .h. But I can't figure it
> out. Help!
Sorry, there is no such rule as in makefile. You have to add_custom_commad()
for each .h file.
If you have a list of files, then you could achieve the effect of ".h.i" rule
like this:
file(GLOB hlist ${CMAKE_CURRENT_SOURCE_DIR}*.h)
foreach(hfile ${hlist})
get_filename_component(hbase ${hfile} NAME_WE)
add_custom_command(
OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/${hbase}.i"
COMMAND ${CMAKE_CXX_COMPILER}
ARGS -E ${hfile} > "${CMAKE_CURRENT_BINARY_DIR}/${hbase}.i"
DEPENDS ${hfile}
)
SET_SOURCE_FILES_PROPERTIES("${CMAKE_CURRENT_BINARY_DIR}/${hbase}.i"
GENERATED)
endforeach()
But, why not rename xx.h into xx.cpp?
> I'd also appreciate a link to documentation that explains the concepts
> behind cmake. I get the feeling that the online documentation for
> cmake is deliberately sketchy to promote the sales of the book which
> is featured on the main page. It's either making hello-world-type
> projects with three source files and a bit of configuration or
> extremely terse 'Documentation' which has no conceptual explanations
> or examples. You know what cmake syntax reminds me of? Lisp. and that
> has always been good for giving me a headache. There's a down side to
> a simple syntax: it's all in semantics.
I don't have that either.
> Kay
>
Kornel
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