Good Practice With Include Files

I'm writing a library, which has the ability to interoperate with SDL, but in the event that SDL does not exist, is still useful on its own. I want to have it build regardless of whether or not SDL exists, and simply disable functionality.

So far, I have the SDL extensions inside an #ifdef which checks for _SDL_H (SDL.h defines this). I include SDL with the statemene

Code:

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#include "SDL.h"

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Then, I create a folder, "dummy," in which I have a blank file called "SDL.h" The Makefile adds "dummy" to the build path, but after everything else. That way, if the user adds an -I/usr/include/SDL (or whatever form your operating system works with), it gets built with the SDL extensions, but if not, it builds without them. Is this a bad way of implementing everything?

It's not really a bad way, although it'd probably be easier to just have your own definition for SDL.

why not just do this:

Code:

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#ifdef MYPROG_SDL_SUPPORT
#include "SDL.h"
#endif

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Most of the time, what you want to do is "check if there is SDL installed" and set a "CONFIG_HAS_SDL" or some such define on the command-line (or in a "config.h"), so that later on you can do something like:

Code:

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#if CONFIG_HAS_SDL
  #include <SDL.h>
#endif
...
#if CONFIG_HAS_SDL
    .... // some SDL-related code
#endif

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