Sure, a good hack, upvoted. Though, not to state the obvious, but if you find yourself in a need a context for an atexit() callback, then you are doing somethi

Sure, a good hack, upvoted. Though, not to state the obvious, but if you find yourself in a need a context for an atexit() callback, then you are doing something wrong. Similarly, if a library function accepts just a function pointer, then it's either a global callback, or it's a mistake in a library design.