[CMake] Absolute Path linking library

[Laurent Chauvin]

Thank you very much for your answer.

I will try to use the MACOSX_RPATH.

However, I have some questions. As the flag suggests, it's only for mac. Is
there anything similar for Linux (and eventually Windows systems) ?

Also, the problem to set the full path of the library is, if I compile on
Windows the extension of library will be dll, on Mac it will be dyld, and
.a on linux.
I could make a condition to set the extension at the end of the name of the
library like libMyLib.(dll, dyld, a) but, I feel like it's not really a
clean way to do it.

Is there a better way to do it ?

Thank you very much.
-Laurent



On Wed, Sep 4, 2013 at 10:57 AM, Clinton Stimpson <clinton at elemtech.com>wrote:

> On Tuesday, September 03, 2013 09:47:45 PM Laurent Chauvin wrote:
> > Hello everyone,
> >
> > I'm working on a library, and I would like the users be able to create
> their
> > own program and liking to my library (by specifying path in cmake).
> >
> > I created the library and an example to test it.
> > Everything compiles.
> >
> > However, when I try to run my example I have this error:
> > MyExample:
> >       libMyLib.1.dylib (compatibility version 1.0.0, current version
> 1.0.0)
> >       /usr/lib/libstdc++.6.dylib (compatibility version 7.0.0, current
> version
> > 56.0.0) /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current
> > version 169.3.0)
> >
> > The problem is my example is not in the same directory as my library (not
> > even in a subdirectory). And it seems it's linking to my library with a
> > relative path.
> >
> > If I add the path of my library in DYLD_LIBRARY_PATH it works, but I
> would
> > like the users to be able to compile and link straight forward.
> >
> > To link the library to my example I use find_package(MyLib REQUIRED) and
> > include(${MyLib_USE_FILE}) which basically do a LINK_DIRECTORIES with the
> > absolute path of the library.
> >
> > Then I do add_executable and target_link_libraries(MyExample
> > ${MyLib_LIBRARIES})
> >
> > Compilation is working fine. There is these options:
> >
> > -L/Absolute/Path/To/MyLib -lMyLib
> >
> > But at runtime, library cannot be found.
> >
> > Would it be possible to put the full path of my library when linking in
> the
> > CMakeLists ?
> >
>
> You should use the full path to the library instead of LINK_DIRECTORIES.
> Its easiest if you use install(EXPORT ...) to have CMake generate an export
> file for you that can be included by your FindMyLib.cmake file.
> That export file will use the full path, and include any other necessary
> information about the library.
>
> But to solve the problem of finding the library at runtime (specifying a
> full
> path won't solve it), CMake 2.8.12 has a new feature to address exactly
> that
> problem.  For details: http://www.kitware.com/blog/home/post/510
>
> If you can use CMake 2.8.12, then you need to put
>  set(MACOSX_RPATH 1)
> in the CMakeLists.txt of MyLib.
>
> If the user is using 2.8.12, then any executable they compile with your
> library will be able to find the library, no matter where it is.
>
> By the way, 2.8.12 is in a release candidate stage right now, and right now
> would be a good time for you to test the new feature that is meant to solve
> your problem.
>
> Clint
>



-- 
Laurent Chauvin, MS
Surgical Navigation and Robotics Laboratory, Radiology Department
Brigham And Women's Hospital, Harvard Medical School
http://wiki.ncigt.org/index.php/User:Lchauvin
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