Nested Class member function can't access function of enclosing class. Why?

Question

Please see the example code below:

class A { private:     class B     {     public:         foobar();     }; public:     foo();     bar(); }; 

Within class A & B implementation:

A::foo() {     //do something }  A::bar() {     //some code     foo();     //more code }  A::B::foobar() {     //some code     foo(); //<<compiler doesn't like this } 

The compiler flags the call to foo() within the method foobar(). Earlier, I had foo() as private member function of class A but changed to public assuming that B's function can't see it. Of course, it didn't help. I am trying to re-use the functionality provided by A's method. Why doesn't the compiler allow this function call? As I see it, they are part of same enclosing class (A). I thought the accessibility issue for nested class meebers for enclosing class in C++ standards was resolved.

How can I achieve what I am trying to do without re-writing the same method (foo()) for B, which keeping B nested within A?

I am using VC++ compiler ver-9 (Visual Studio 2008). Thank you for your help.

Answer 1

foo() is a non-static member function of A and you are trying to call it without an instance.
The nested class B is a seperate class that only has some access privileges and doesn't have any special knowledge about existing instances of A.

If B needs access to an A you have to give it a reference to it, e.g.:

class A {     class B {         A& parent_;     public:         B(A& parent) : parent_(parent) {}         void foobar() { parent_.foo(); }     };     B b_; public:     A() : b_(*this) {} };