title: How to build a library directly from object files with CMake
body: <p>Given a set of object files, how would you build a static library with CMake ?</p>
  
  <p>With autotools I would do </p>
  
  <pre><code>libXXX.a: $(OBJFILES)
      $(AR) cru $@ $(OBJFILES)
      $(RANLIB) $@
  </code></pre>
  
  <p>OBJFILES being a list of object files. </p>
  
  <p>How to do that in CMake ? </p>
  
  <p>EDIT: I can't recompile the original cxx files, I have to use the object files (*.o) to create the library.</p>