patil@bnr.ca (Vinayak Patilkulkarni) writes:

>I have a problem declaring a templated class as friend. C++ programming
>language does not seem to handle it.

Bingo.

However, Cfront has always allowed friend templates, and I think
the committee does want to allow this sort of thing.
The current draft is somewhat schitzophrenic on the issue.

>class QElem {
>private :
>    void stamp () {}
>    friend class Q;
>    // What i intend to do here is to make stamp()
>    // as friend function of all Q<T> classes.

To do that, you would have to write

 class QElem {
 private :
     void stamp () {}
     template <class T> friend class Q<T>;

However, as noted above this usage is somewhat dubious, and is
not supported by some compilers.

>    // ObjectCenter compiler takes the above line and makes
>    // stamp () as friend function of all types of Q.
>    // However g++ compiler flags the error. (gnu g++ 2.6.2)

ObjectCenter is wrong.  There is a big difference between a template-name
and a class-name.  In your example, `Q' is a template-name, not a class-name.

>But it does not solve my problems, as my library is expected to run
>with different compliers.

In that case, don't use template friends.
Just make QElem::stamp() public (with some appropriate documentation).

--
Fergus Henderson                       | I'll forgive even GNU emacs as
fjh@cs.mu.oz.au                        | long as gcc is available ;-)
http://www.cs.mu.oz.au/~fjh            |             - Linus Torvalds

Hi,

I have a problem declaring a templated class as friend. C++ programming
language does not seem to handle it.

Consider the simple example given below.

#include <iostream.h>

class QElem {

private :
    void stamp () {}
    friend class Q;
    // What i intend to do here is to make stamp()
    // as friend function of all Q<T> classes.
    // ObjectCenter compiler takes the above line and makes
    // stamp () as friend function of all types of Q.
    // However g++ compiler flags the error. (gnu g++ 2.6.2)
};

template <class T> class Q {

public:
    void add (T* p) { p->stamp (); }
};

class A : public QElem {};

void main ()
{
    Q<A> x;
    x.add (new A);
}

Now the question is which one is correct ?
ObjectCenter
 or GNU ?
or It is not defined been handled by the language.

r.14.7 in Reference manual of C++ programming lang II edition does not
list such an example.

I am happy to accept the feature (or bug) provided by ObjectCenter CC.
But it does not solve my problems, as my library is expected to run
with different compliers.

- Patil

#opinions are mine only.