[CMake] Creating custom file before building/compiling with cmake

[Michael Wild]

In that case I recommend creating a CMake script (e.g. create_application_version.cmake) which creates the ApplicationVersion.xml file. It queries the current revision (have a look at FindSVN.cmake on how to do this), determines the date and time (this is a problem, refer to this thread for more info: http://www.mail-archive.com/cmake@cmake.org/msg30662.html) and then either does a configure_file() or a file(WRITE) to create ApplicationVersion.xml. Ideally the create_application_version.cmake is also a configured file (with the path to the build and source tree and the path to the svn executable etc.).

This script is then invoked by a custom command:

# dummy_file is never created...
add_custom_command(OUTPUT ${CMAKE_BINARY_DIR}/ApplicationVersion.xml ${CMAKE_BINARY_DIR}/dummy_file
  COMMAND ${CMAKE_EXECUTABLE} -P ${CMAKE_BINARY_DIR}/create_application_version.cmake
  COMMENT "Creating ApplicationVersion.xml"
  VERBATIM
  )

# this intentionally depends on dummy_file, which is never created
add_custom_target(create_appplication_version ALL
  DEPENDS ${CMAKE_BINARY_DIR}/ApplicationVersion.xml ${CMAKE_BINARY_DIR}/dummy_file)

add_executable(super_duper main.cpp ${CMAKE_BINARY_DIR}/ApplicationVersion.xml)
add_dependencies(super_duper create_appplication_version)


The trick I'm trying to pull off, is that super_duper depends on create_appplication_version, which is always out of date and depends on the non-existing file dummy_file, thus always updating ApplicationVersion.xml. Not that I haven't tested this.

Michael

On 19. Aug, 2010, at 18:54 , Roman Wüger @mac.com wrote:

> The file should be updated every time a build is started.
> 
> Best Regards
> NoRulez
> 
> Am 19. Aug 2010 um 16:48 schrieb Michael Wild <themiwi at gmail.com>:
> 
>> 
>> On 19. Aug, 2010, at 16:38 , Roman Wüger @mac.com wrote:
>> 
>> > Hello,
>> >
>> > i need to create a file called "ApplicationVersion.xml" before the main source file (main.cpp) would be compiled.
>> > The file should contain some application details and the current Date/Time and SVN Revision.
>> >
>> > How can I create such file before the source file are compiled?
>> > How can I get the current Date/Time and the SVN Revision?
>> >
>> > Thanks in advance
>> >
>> > Best Regards
>> > NoRulez
>> 
>> 
>> When should the file be updated? At configure time or every time a build is started?
>> 
>> Michael