[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