Hi All,

I wanted to know how to declare a friend function which is a member
function of a different class.

Eg:
/* Class which contains the member function to be declared as friend
*/
template <class T, int W>
class A
{
B obj;
public:
void foo(T val); // Function to be declared as a friend.
}

template <class T, int W>
void A<T,W>::foo(val)
{
obj.val = val;
}

/* Class inside which the friend function is to be declared */
template <class U>
class B
{
U val;
public:
friend A<class T, class W>::foo(W val); // Declare friend.
}

I cant seem to get the syntax right. Please let me know.

Thanks
Rakesh

getrakesh@gmail.com schrieb:
> /* Class inside which the friend function is to be declared */
> template <class U>
> class B
> {
> U val;
> public:
> friend A<class T, class W>::foo(W val); // Declare friend.
> }
>
> I cant seem to get the syntax right. Please let me know.

Something like that.

template <class U>
class B
{
U val;
public:
template <int W>
friend void A<U, W>::foo(); // Declare friend.
}

But this won't work for your purpose anyway because of the cyclic
dependancy of the definitions of class A and class B. A need to be
defined befor B because the friend declaration won't work otherwise. B
needs to be defined before A because it is a member of A.


Marcel

On 26 Feb, 10:34, getrak...@gmail.com wrote:
> Hi All,
>
> I wanted to know how to declare a friend function which is a member
> function of a different class.
>
> Eg:
> /* Class which contains the member function to be declared as friend
> */
> template <class T, int W>
> class A
> {
> B obj;

This causes a circular dependency. Also you are missing B's template
parameter

> public:
> void foo(T val); // Function to be declared as a friend.
> }
>
> template <class T, int W>
> void A<T,W>::foo(val)
> {
> obj.val = val;
>
> }
>
> /* Class inside which the friend function is to be declared */
> template <class U>
> class B
> {
> U val;
> public:
> friend A<class T, class W>::foo(W val); // Declare friend.

Try:
template<class T, int W>
friend void A<T,W>::foo(W);
>
> }
>
> I cant seem to get the syntax right. Please let me know.

Hope this s.
DP