Placing C++ libs out of global namespace

Question

So I'm building a c++11 library based on other libraries like opengl, SDL2, assimp,glm, etc... Only problem is that most of those libraries place their functions, or objects in the global namespace : this may conflict with my classes ! (for ex. assimp vectors and my Vector class...) So I thought of putting the libraries in a namespace instead of leaving them there to "pollute" the global namespace.

I thought of doing this :

namespace some_name_space
{
   #include <some/kind/of/lib>
}

But I realized that there would still be a part of the library in the global namespace !

Any suggestions on how achieve this ?

PS : I could "wrap" the libs, but that wouldn't really be managable !

Answer 1

I guess what you want is placing all library's functions and classes into a namespace.

In this answer, I'll use gl/gl.h for an example.

As far as I know, the line #include <gl/gl.h> will be replaced by all the code from gl/gl.h.

if you want to move all classes and functions from gl/gl.h into a namespace (gl for example), I should create an intermediate file called __gl.hpp with a content like:

namespace gl {
  using namespace gl; //because gl/gl.h don't know namespace gl
  #include <gl/gl.h>
  //#include more and more kind of libraries which use namespace gl
}

Then, in your main file, use #include "__gl.hpp" instead of #include <gl/gl.h>

Note that macros may not be moved into namespace gl, because they're macros.

But don't worry, because:

• Almost macros have an UPPERCASE identifier and almost non-macros are lowercase or UpperAndLowerCase or lowerAndUpperCase or lower_case_and_underscore ...

• If a macro is being redefined, the compiler will give you a warning. So, you needn't worry about namesake macro.

This way is also applicable for windows.h and some other libraries, but it can't be applied for almost C/C++ standard library.

Answer 2

Apparently, that is possible to do with pure C libraries. However, that's probably not a good idea to do.

As far as I know, C++ doesn't provide the utilities for what you are trying to do. Your best option is just to put the includes in the source files instead of the header files, at least for the publicly exposed API. This way there shouldn't be any conflicts, as long as there aren't any conflicts between the libraries you are including in a single source file. If there are still conflicts you will have to wrap the items you are using in the conflicting header individually.

Also, you may consider putting your own classes within a namespace to reduce chance of conflict.