How to create a NSAutoreleasePool without Objective-C?

Question

I have multiplatform game written in C++. In the mac version, even though I do not have any obj-c code, one of the libraries I use seems to be auto-releasing stuff, and I get memory leaks for that, since I did not create a NSAutoreleasePool.

What I want is to be able to create (and destroy) a NSAutoreleasePool without using obj-c code, so I don't need to create a .m file, and change my build scripts just for that. Is that possible? How can that be done?

OBS: Tagged C and C++, because a solution in any of those languages will do.

Answer 1

You can't avoid instantiating the Objective-C runtime—but apparently you've already got one of those.

If you want to interact with the runtime from C, you can us the Objective-C runtime APIs, as documented in Objective-C Runtime Programming Guide and Objective-C Runtime Reference.

The idea is something like this (untested):

#include <objc/runtime.h>
#include <objc/objc-runtime.h>
id allocAndInitAutoreleasePool() {
  Class NSAutoreleasePoolClass = objc_getClass("NSAutoreleasePool");
  id pool = class_createInstance(NSAutoreleasePoolClass, 0);
  return objc_msgSend(pool, "init");
}
void drainAutoreleasePool(id pool) {
  (void)objc_msgSend(pool, "drain");
}

If you want to call these functions from another file, of course you'll have to include objc/runtime.h there as well. Or, alternatively, you can cast the id to void* in the return from the allocAndInit function, and take a void* and cast back to id in the drain function. (You could also forward-declare struct objc_object and typedef struct objc_object *id, but I believe that's not actually guaranteed to be the right definition.)

You shouldn't have to pass -lobjc in your link command.

Needless to say, it's probably less work to just make your build scripts handle .m files.