c_mem_safety/handle.h

#ifndef MAG_HANDLE_H
#define MAG_HANDLE_H

#ifdef __cplusplus
#error "handle.h does not work with C++ compilers, you must compile these files with GCC directly!"
#endif

/** Tells your constructor/destructor handler function about the state */
enum HANDLE_STATE {
	HANDLE_CREAT,
	HANDLE_DESTR,
};

/**
 * This creates a "handle". Basically a struct with given constructor and destructor + RAII.
 *
 * Usage:
 *
 * struct Meaning {
 * 		int a;
 * 		int b;
 * };
 * // You can typedef if you want, change code accordingly!
 *
 * handle(struct Meaning) {
 * 	if(state == HANDLE_CREAT) {
 * 		this->a = *(int*) data;
 * 		this->b = 2
 * 	} else {
 * 		printf("%d\n", this->a + this->b);
 * 	}
 * }
 *
 * // Now you can use a handle in your local scopes
 * // Should print 42:
 * int main() {
 * 		int initializer = 40;
 * 		creat(struct Data, d, &initializer);
 * }
 *
 * Rem.: Unrelated trick, but you can typedef struct A A; // both typedef and forward declare
 */

#define creat(TNAME, VNAME, VINIT) \
	[[gnu::always_inline]] inline void F(TNAME *v) { \
		TNAME##_lifetime_handler(HANDLE_DESTR, v, NULL); \
	} \
	[[gnu::cleanup(F)]] TNAME VNAME; \
	TNAME##_lifetime_handler(HANDLE_CREAT, VNAME, VINIT);

#define handle(TNAME) \
	static [[gnu::always_inline]] inline void TNAME##_lifetime_handler( \
		HANDLE_STATE state, \
		TNAME *this, \
		void *data)

#endif // MAG_HANDLE_H