1.1. Point to the function pointer of the member function
1.1.1. Static member function pointer
Double (Point :: * Coord) () = & point :: x;
Coord pointing to the actual address of X.
1.1.2. Non-virtual non-static member function pointer
Double (Point :: * Coord) () = & point :: x;
The pointer is obtained is the true address of X in memory, but this value is not complete, he needs to be bound to a Class Object address to call the function. The above pointer call:
a) (Origin. * Coord) ();
b) (PTR -> * coord) ();
Will be transformed into:
a) (& Origin);
b) (COORD) (PTR);
Such call costs, if you don't have Virtual, multiple inheritance or virtual base clars, is not high than non-member function pointers.
1.1.3. Virtual member function pointer
Double (Point :: * Coord) () = & point :: x;
The pointer is obtained is the index value of X in the Virtual Table.
(PTR -> * coord) ();
Will be converted to:
(* PTR-> VPTR [(int) Coord]) (PTR);
So how can you know that COORD makes the address or index? This must be introduced into a more general rule.
1.1.4. Member function pointer under multiple inheritance
0001 struct _mptr0002 {0003 INT DELTA; // THIS pointer's OFFSET value 0004 int index; // VTBL 0005 Union 0006 {0007 PTRTOFUNC FADDR; / / Function address 0008 INT V_OFFSET; // Virtual or multiple inheritance Two or subsequent Base Class VPTR
//, if the VPTR is placed in the beginning of the object, it is useless, the price is compatible.
/ Decrease 0009}; 0010};
(PTR -> * coord) ();
Will be converted to:
(Coord.index <0)
? // Non-virtual function
(* coord.faddr) (PTR)
: // virtual function
(* ptr-> vptr [coord.index] (PTR));
1.2. Function efficiency
effectiveness
name
high
Low Inline Menber Non-member Function (Nomember) Static member function (Nostatic Member) MEMBER Multi-inheritance Function (Virtual MEMBER) Virtual Inheritance Function (Virtual MEMBER) )
1.3. Function pointer efficiency
effectiveness
name
high
Pointer to non-member function Pointer Pointer Pointer Multiple Inheritance Non-virtual Function Pointer Multiple Inherited Non-virtual Function Pointer Pointer Pointer Pointer Pointer Pointer Multi - inherited Multi - inherited Virtual Members Function Pointer
