Possibly stupid question?
Hi all
This question may be stupid..
but why can't I declare an object like this:
Object instance = [[Object alloc] init];
Instead why do I have to do
Object *instance = [[Object alloc] init];
Just curious..
Because you can't actually create an object! What you do is to allocate an object in memory (from the heap) and you have a pointer to it. That's what Object* instance means!
If you created an object on the stack with:
Object deadOnArrival ;
several things would happen including:
1) the object would be on the stack
2) the object wouldn't call alloc or init
3) the object will go out of scope at the end of the current block ( the } syntax ) and would not call its release or dealloc methods
4) to call a method on that object you'd have to say [&object myMethod....]; (not nice at all)
- in short you're in deep trouble.
C++ addresses all of those matter - however you're in the land of Obj/C and the rules of C apply to Obj/C.
I agree that having to put the * thing on the line in which you declare is irritating. However, just accept it and you'll soon be happy. Fight it and you'll be sorry!
Wow, interesting. It almost seems natural though, to have *instance *thang. It looks cool.
I personally always write that as:
NSObject* instance = bla bla
and not as:
NSObject *instance = bla bla
The name of the variable is called instance (and it's of type NSObject*). The name is NOT called *instance (of type NSObject). Sadly, all the Apple code uses the *instance style of declaration.
In the "C" language you can declare things like this:
int fred, *pointerToFoo, vomit, nonesense, *anotherWeePtr;
In my opinion there 2 serious defects of C language demonstrated here:
1) You shouldn't be allowed to declare more than one variable at a time.
2) Even if you could declare multiple variable, I would not allow the * on the variable name - I'd put it on the type. So I'd have:
int fred, vomit, nonesense ;
int* pointerToFoo, anotherWeePtr;
However, leaving aside my dislike of the *instance thing, let's return to the NSObject*. I agree it's kind of odd. However that's C. You'll have to accept it - it isn't going to change.
