I used macros in my libraries for overriding the allocation functions before, but have switched to runtime callbacks later, same for logging btw (I'd need to lo

I used macros in my libraries for overriding the allocation functions before, but have switched to runtime callbacks later, same for logging btw (I'd need to look through the issues list for the exact reasons which led to this decision though). In any case, passing callbacks as part of the initialization "feels" right and I didn't hear any complaints since the switch (and it's definitely a lot more convenient for the library user). Also, if the library calls those function so frequently that the pointer indirection would be a performance problem, then there's arguably something very wrong with the library's design.