Re: [OT] #define

[Andrew Edwards via Digitalmars-d-learn]

On Monday, 22 May 2017 at 13:15:31 UTC, Adam D. Ruppe wrote:
On Monday, 22 May 2017 at 13:11:15 UTC, Andrew Edwards wrote:
    #ifndef THING
    #define THING
    #endif

This kind of thing is most commonly used in include guards

https://en.wikipedia.org/wiki/Include_guard#Use_of_.23include_guards

Have a basic understanding. In the specific case i'm looking at, 
they are not used as include guards though.

You can usually just strip that out in D, since the module 
system already just works if imported twice.

Makes sense.

    #ifndef SOME_THING
    #define SOME_THING THING *
    #endif

Is this equivalent to:

    alias thing = void;
    alias someThing = thing*;

I'd have to see that in context though to see why they are 
doing it... it is probably some kind of platform specific type 
definitions.

Specific context at the following links:

https://github.com/glfw/glfw/blob/66ff4aae89572419bb130c5613798e34d7521fc7/deps/glad/glad.h#L24-L48

https://github.com/glfw/glfw/blob/66ff4aae89572419bb130c5613798e34d7521fc7/deps/glad/glad.h#L57-L81

https://github.com/glfw/glfw/blob/66ff4aae89572419bb130c5613798e34d7521fc7/deps/glad/glad.h#L88-L124

Thanks,
Andrew