[CMake] does CMake have "usage targets" like Premake?

[Lance Luvaul]

I think cmake's find_package is only a first order approximation to 
premake's usages.  What usage library targets have that find_package 
doesn't is the ability to cleanly inject dependency info (like include 
dirs or link libraries) into any target that claims to be dependent on 
the library.  This is achieved simply by having the target call "uses 
<library>"... there is no need for the target to explicitly add anything 
to target_link_libraries() or include_directories().

I guess it's a bit like calling include_directories() twice, once in the 
CMakeLists.txt for the library and again in the CMakeLists.txt file for 
the target using the library, but then you'd need to have the latter 
include() the former for it to work (as having target 
add_subdirectory(library) wouldn't have the same accumulative effect).  
But for accumulating all linker objects together, this wouldn't work 
(that is, having target call target_link_libraries() on its binaries 
then include()'ing another file defining library which calls 
target_link_libraries() for its binaries).  Target would have to either 
add something via target_link_libraries() or call 
add_dependencies(target library).

I guess the crux of it is that target shouldn't have to concern itself 
with library's business.  It should be library's job to add library's 
header paths to include_directories(), or its binaries to 
target_link_libraries().  Target should only add its own header paths 
and binaries.  It's the whole 'separation of concerns' or 'modular 
object programming paradigm' argument.

I guess I'd say usages seem to be like a combination of 
include_directories, add_dependencies and target_link_libraries, but 
done in a more succinct way and put in their proper place.  Apart from 
the succinctness, can this be done in CMake?


On 16/01/2012 11:54 PM, Yuri Timenkov wrote:
>
> if i understand correctly it's CMake's find_package analog.
>
> On Jan 16, 2012 10:41 AM, "Lance Luvaul" <lance at mso.anu.edu.au 
> <mailto:lance at mso.anu.edu.au>> wrote:
>
>     See
>     http://sourceforge.net/tracker/index.php?func=detail&aid=2794681&group_id=71616&atid=531880
>     <http://sourceforge.net/tracker/index.php?func=detail&aid=2794681&group_id=71616&atid=531880>
>     for more detail on what constitutes a usage-target.   How can I
>     achieve the same result in CMake?  Thanks.
>     --
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