[CMake] ExternalProject dependency question

[David Cole]

On Thu, Oct 27, 2011 at 7:07 PM, Dan Kegel <dank at kegel.com> wrote:
> Oh, man, now I get it.
> The idea of http://www.cmake.org/Bug/view.php?id=10395
> is to tell cmake that the external project is generating a library;
> you can then hang the dependencies on that library.
> Here's an example that seems works for me (tested by inserting a big
> sleep into the configure for the external project):
>
> cmake_minimum_required (VERSION 2.8.4)
> include(ExternalProject)
> ExternalProject_Add(
>    Foobar_external
>    SOURCE_DIR ${CMAKE_SOURCE_DIR}/foobar
>    INSTALL_DIR ${CMAKE_BINARY_DIR}/prefix
>    CONFIGURE_COMMAND ${CMAKE_SOURCE_DIR}/foobar/configure
> --prefix=${CMAKE_BINARY_DIR}/prefix
> )
> # Tell cmake that the external project generated a library so we can
> add dependencies here instead of later
> add_library(Foobar UNKNOWN IMPORTED)
> set_property(TARGET Foobar PROPERTY IMPORTED_LOCATION
> ${CMAKE_BINARY_DIR}/prefix/lib/libfoobar.a )
> add_dependencies(Foobar Foobar_external)
> SET(Foobar_INCLUDE_DIR ${CMAKE_SOURCE_DIR}/foobar)
> SET(Foobar_LIBRARIES Foobar)
>
> # Now callers of library Foobar can just do
> #   target_link_libraries(whatever ${Foobar_LIBRARIES})
> # instead of
> #   target_link_libraries(whatever ${Foobar_LIBRARIES})
> #   add_dependencies(whatever ${Foobar_LIBRARIES})
>
> That sound right?

Yes. I think you do get it now. :-)


>
> I wonder if this couldn't be wrapped up more neatly somehow, but for
> now, it's better than what I was doing before.
> - Dan
>

I'm sure it could: sounds like it's time for another article for The
Source, or a blog entry, or something.


Cheers,
David