Getting undefined reference error at adding simple class to library

I am working with a rather sizeable library which uses CMake for compilation/linking. I need to add some functionality, thus I need to add some classes to the library. The problem is that when I add even a simple helloWorld class to the library, and try to call it from some main function, I get undefined reference problem at link time. When I looked into the built code ("CMakeFiles" within the library folder), my class hasn't been compiled by CMake (and thus, for开发者_Python百科 instance, there is no HelloWorld.o file in there).

Can somebody point out where I am going wrong? Do I need to explicitely tell CMake to compile this class? (if yes, how?). I am novice in CMake, so don't know how to tackle this problem.

I call the function like this. ``

GSROrdinary sord;

The error message, I get, is something like this.

undefined reference to beep::GSROrdinary::GSROrdinary()
undefined reference to beep::GSROrdinary::~GSROrdinary()

Yes, you need to tell CMake to compile your class. I suggest that you check out some CMake tutorials that can be found online. Here is a nice one: http://www.cs.swarthmore.edu/~adanner/tips/cmake.php - pay particular attention to the CMakeLists.txt file and syntax. You will have to modify your lib's CMakeLists.txt in order to add a new class.

You have to explicitly add your new file to the CMake file so that they get compiled and linked.

This commented sample could give you a start (basically you have to look for a add_library (LIBNAME files) directive in one of your CMakeLists.txt files and add your new file there, but you should also possibly read the documentation.