Passing address of copy of local object to pointer to base class

[raydona]

Hi,
Can I pass the address of a copy of a local object to a pointer? Say function someFunc(), of a container class L returns a copy of a local object of type X. X is derived from the ABSTRACT class Y.

X L::someFunc()
{ X local;
// rest of code
return X;
}

How can I pass the object returned to a pointer of abstract class Y, that is, say:
L Lobject;
Y* Yptr = &(Lobject.someFunc();

If I do the above I get the compiler error:
'&': illegal operation on bound member function expression

I wonder if anyone can offer a solution. All help will be greatly appreciated.

 

[ArkM]

A function returns a value, not a variable. It's impossible to get an address of a value (for example, you can't write &1).
You may dynamically allocate an object of X in someFunc member function and return a pointer (Y*) to it, but you must delete this object by hand in callee context (it's error-prone approach, of course). Or use some kind of a smart pointer to deallocate this pointer safety at proper context.

 

[cpjust]

L Lobject;
X Xobj = Lobject.someFunc();
Y* Yptr = &Xobj;

 

[ArkM]

I think, explicit declaration of X class temp var makes advantages of polymorphism too weak. If we must know exact type of returned value, why we have interface pointer to Y after that?