Repository navigation
Opaque structs and SDL_net #140
Description
Activity
Which of these solutions do you prefer and why?
I'd prefer to go with the first solution (no
TThing, usePThinginstead) because to me, receiving a "bare" value and a pointer to a value carry different connotations. With a "bare" value, I'd expect to be able to just copy it and voilà, now I have two independent instances ofTSomeType. This is obviously not the case with pointers - if I copy a pointer, both the original and the copy point to the same object and manipulating one of them influences the other.Of course, one can argue that there are plenty of APIs which return "handle" values, which are just ints (or some other primitive type) that identify a resource - like the UNIX
open()API, for example. And well, yeah, if you usesocket(2)you also get the socket as a file descriptor handle - so maybe SDL_net is kinda trying to emulate that?Still, I think that my original point still stands - making it a pointer type should convey to the programmer that they're not dealing with pass-by-value mechanics.
I agree with your point. Usually we try to stay as close to the original code as possible. In this instance though it is potentially confusing. Not only for C programmers, but also for users of our bindings, as we just decided to go for typed pointers for opaque C structures.
We may add a SDL_net hint to this discussion in the cheat sheet opaque structures chapter.
Best regards
In most of SDL headers, opaque structs use the following kind of typedef:
As such, when writing C code, the following variable declaration:
Is resolved by the compiler into:
Which causes a compilation failure, as
struct SDL_Thingis an opaque struct with unknown size. Hence, to declare a pointer variable, the programmer must explicitly declare the variable as a pointer:However, for whatever reason, SDL_net does things differently, and uses the following kind of typedef:
As such, when writing C code, the following variable declaration:
Is resolved by the compiler into:
Which compiles fine, as this creates a pointer variable - unbeknown to the programmer (unless they actually look at the typedef).
So now, my question: how should we handle this in
sdl2_net.pasin terms of type naming?Keep the API similar to other units: make the
TThingunavailable, and only usePThingeverywhere. This makes it clear thatPThingis a pointer to some data the programmer isn't meant to touch.Keep the API close to the original C headers, and use
TThing. This obscures the information thatTThingis a pointer.