[CMake] How to get a variable that is defined in another CMakeLists.txt file

[Mike Jackson]

On Dec 20, 2006, at 3:15 PM, Axel Roebel wrote:

> On Wednesday 20 December 2006 17:27, Mike Jackson wrote:
>> That did not seem to work either. Basically I am trying to set a
>> place where we can set the names of the libraries and apps and have
>> those found by other projects that depend on these base libraries.
>>
>>    I have noticed that if you "INCLUDE(${PROJECT_SOURCE_DIR}/
>> FindHDF.cmake)" a file, in this case our module to find HDF, then
>> those variables are found..  So I guess I could have a Names.cmake
>> file where these variables are defined and then include that file in
>> each CMakeLists.txt file for the project..
>>
>> Kinda seems like a heavy handed way to do this..
>  For a single variable  PORTAUDIO_LINK_LIBRARIES)
> defined in a sub directory "portaudio"
> this definitely works for me.
>
>  GET_DIRECTORY_PROPERTY(outvar DIRECTORY portaudio
> DEFINITION PORTAUDIO_LINK_LIBRARIES)
>
> If you use DEFINITIONS as suggested earlier here you get outvar to  
> contain a
> text with all definitions   made in the sub dir which is not what  
> you want.
>
> Note, that with get_directory_property the output variable
> will always be set - to an empty string if the the variable
> in the directory is not set. So testing for undefined
> state is probably not working with this scheme.
>
> You can however test for empty values
> and -NOTFOUND and the like.
>
> cheers
>
> -- 
> Axel Roebel
> IRCAM Analysis/Synthesis Team
> Phone: ++33-1-4478 4845 | Fax: ++33-1-4478 1540

Well I am just NOT getting this.. So let us start over. I think there  
was some confusion about the IF(). I had that in there for simple  
debugging. I do not really need it.

I have Project A and Project B. Both of their directories are at the  
same level in the file system.
Project A builds a library which is needed in Project B. This part is  
not the problem. The problem is that we may need to change the name  
of the Library produced by Project A. So in Project A's  
CMakeLists.txt file I have the following:

SET (A_LIB_OUTPUT_NAME "MyGreatLibrary")
And I use that variable farther down in the same CMakeLists.txt file  
such as:
ADD_LIBRARY( ${A_LIB_OUTPUT_NAME} ${SOURCES} )

NOW.. on to Project B's CMakeLists.txt file. As I said, Project B is  
going to link against Project A's library but I would like to be able  
to use ${A_LIB_OUTPUT_NAME} in Project B's CMakeLists.txt file.

So in Project B's CMakeLists.txt file I have:
....
SUBDIRS(${PROJECT_SOURCE_DIR}/Project_A)
....
ADD_EXECUTABLE( MyProgram ${SOURCES})
TARGET_LINK_LIBRARIES( MyProgram ${A_LIB_OUTPUT_NAME})

In my situation, ${A_LIB_OUTPUT_NAME} is never built because the  
variable ${A_LIB_OUTPUT_NAME} is empty. How do I get the value for  
A_LIB_OUTPUT_NAME to be what it is in Project A?

Sorry for any confusion I created earlier for having a poorly  
commented example. I hope this explains better what I am trying to  
do. I would like it this way so that we only have to change the name  
of Project A's library in ONE place.. at the moment I have it set in  
_every_ CMakeLists.txt file that I use it in.. which is error prone.

This is on CMake 2.4.3 and OS X 10.4.8.
-- 
Mike Jackson   Senior Research Engineer
Innovative Management & Technology Services