[CMake] Fwd: Targets organisation of complex project

[Chris Foster]

On Mon, Oct 12, 2009 at 12:57 PM, Pau Garcia i Quiles
<pgquiles at elpauer.org> wrote:
[...]
> What are the advantages of this? Why don't you rename you
> "project.cmake" files to "CMakeLists.txt" and use add_subdirectory on
> those directories? I see no difference :-?

The difference is becase custom code generation rules seem to be local to
subdirectories.  I've made up an example (attached as a tgz file) to
demonstrate what I mean.  The directory layout is:

CMakeLists.txt
libA/
     CMakeLists.txt
     hello2.in.cpp
     hello.cpp
libB/
     CMakeLists.txt
     goodbye.cpp


And inside CMakeLists.txt, I want to build a shared library "libgreeting" which
consolidates all the sources together, that is, all of

  hello.cpp
  hello2.cpp (generated from libA/hello2.in.cpp)
  goodbye.cpp


The problem is that when hello2.cpp is generated, I would like to specify the
generation rules (with add_custom_command) inside libA/CMakeLists.txt to have
everything for libA nicely encapsulated in one place.  However, the build rules
created by add_custom_command seem to be local to the libA subdirectory, and I
don't know how to get the base CMakeLists.txt to see them when using
add_subdirectory().  With include() this problem goes away because the build
rules are actually included into the current file.

Try to run the simple example I'm attaching and you'll see that cmake complains
about not knowing how to build hello2.cpp.  Setting the GENERATED property
in the base CMakeLists.txt doesn't help because although it allows cmake to
generate the build system, the make stage then fails.


Mateusz: You may find the example layout I've attached useful if you're not
needing to do code generation (just delete all the stuff to do with
hello2.cpp).  You might also consider pulling definitions from the
subdirectories into the base CMakeLists.txt using something like

  get_directory_property(libA_srcs DIRECTORY libA DEFINITION srcs)

rather than pushing them from the subdirectories into the base scope with
set(... PARENT_SCOPE)


~Chris
-------------- next part --------------
A non-text attachment was scrubbed...
Name: cmake_lib_consolidate_eg.tgz
Type: application/x-gzip
Size: 1474 bytes
Desc: not available
URL: <http://www.cmake.org/pipermail/cmake/attachments/20091012/460ef961/attachment-0001.bin>