gistfile1.txt

// These function pointers are intialized to point to objc_msgSend but with specific
// signatures to help clarify what the selector's expected signature and behavior are.
extern NSString* (*PerformSelectorReturningAutoreleasedString)(id, SEL);
extern NSString* (*PerformSelectorWithObjectReturningAutoreleasedString)(id, SEL, id);
extern id (*PerformSelectorReturningAutoreleasedObject)(id, SEL);
extern void (*PerformSelectorWithObjectReturningVoid)(id, SEL, id);

// To safely dynamic message an object where we expect a BOOL response, we
// need to clue the compiler into the situation sufficiently (this is especially
// broken on Intel if we don't do this).
extern BOOL (*PerformSelectorReturningBOOL)(id, SEL);
extern BOOL (*PerformSelectorWithObjectReturningBOOL)(id, SEL, id);

--------

NSString* (*PerformSelectorReturningAutoreleasedString)(id, SEL) = (NSString* (*)(id, SEL)) objc_msgSend;
NSString* (*PerformSelectorWithObjectReturningAutoreleasedString)(id, SEL, id) = (NSString* (*)(id, SEL, id)) objc_msgSend;
id (*PerformSelectorReturningAutoreleasedObject)(id, SEL) = (id (*)(id, SEL)) objc_msgSend;
void (*PerformSelectorWithObjectReturningVoid)(id, SEL, id) = (void (*)(id, SEL, id)) objc_msgSend;

BOOL (*PerformSelectorReturningBOOL)(id, SEL) = (BOOL (*)(id, SEL)) objc_msgSend;
BOOL (*PerformSelectorWithObjectReturningBOOL)(id, SEL, id) = (BOOL (*)(id, SEL, id)) objc_msgSend;

---------

- (NSString *) rsScriptingValueForSelector:(SEL)selector
{
	NSString *s = PerformSelectorReturningAutoreleasedString(self, selector);
	if (!s)
	{
		return @"";
	}
	return s;
}