[CMake] Generating Source Files

[Bill Hoffman]

Bill Hoffman wrote:
> Jeremy Cowgar wrote:
> 
>>
>> I was hoping to not have to run cmake all the time. I don't want to 
>> have to worry if I edit parser.e, and it ads a new .c file to build, 
>> if I am compiling that new file or not. 1/2 the time I'll never know 
>> if parser.e was updated in such a way.
>>
>> I'm beginning to think that CMake just isn't up to the task and maybe 
>> we should stick with our three makefiles :-/ With the makefiles, we 
>> have a dependency on the .e files, if they change, then we launch 
>> $(MAKE) generate ... Then when we go to build our project, we do 
>> $(MAKE) compile ... This allows us to easily include the .mak file the 
>> generator creates. the first time around it's empty, but it doesn't 
>> matter because when the actual sources are compiled, make is launched, 
>> the Makefile is parsed again and this time (because it's after 
>> generation) the .mak file has content and everything is built 
>> automatically. All we do currently is "make" and everything is handled 
>> for us. It's just getting burdensome maintaining three makefiles.
>>
> 
> OK, so your current make solution runs make recursively to solve the 
> problem.
> 
> To get this to work in CMake you will have to run cmake recursively.  In 
> CVS CMake cmake has a --build command that can be used to drive a build. 
>  In 2.6, you can use ctest --build-and-test to cmake and the build tool 
> automatically.
> 
> So, you create a custom command that runs your parser and creates a full 
> CMakeLists.txt file to build the output of the parser.  Then run ctest 
> --build-and-test on that directory to build the parser output.   What is 
> the output of the parser?  Is it a program or a library, or both?
> 

One more option would be to run the parser every time cmake is run.  If 
you had an option to the parser that just spit out the list of files you 
needed to compile, and it ran relatively fast, you could do this:

# only run if parser.e is newer than source.cmake
if(parser.e IS_NEWER_THAN source.cmake)
    execute_process(COMMAND myparser  parser.e --sources sources.cmake)
endif()
# include source.cmake, this file should set some vars
# something like set(SOURCES a.c b.c d.c)
include(sources.cmake)
# now make parser.e an input to cmake, so that cmake will
# re-run when make is run and parser.e changes
configure_file(parser.e parser.e.flagfile)

add_custom_command(  # add the custom command to run the full parser here)

-Bill