TITLE: class template friend declaration syntax

(Newsgroups: comp.lang.c++.moderated, 13 Feb 98)


GUERVOS: jmerelo@kal-el.ugr.es (J.J. Merelo Guervos)

Hi,
	I have been looking everywhere, and can't find a
solution to this: How should a class template be declared
as a friend?

1. template <class T> friend class A<T>;
2. friend template <class T>  class A<T>;

[snip]


VANDEVOORDE: David Vandevoorde <daveed@cup.hp.com>

It should be:

  3. template<class T> friend class A;

Note that you cannot designate a partial specialization
to be a friend (which is kind of what your syntax implies).
The declaration above also grants access to partial
specializations and (full) specializations.

OTOH, you _can_ designate a (full) specialization of a
class template to be a friend... but them it's no longer
a template. E.g.,

  4. friend class A<bool>;

Friend function template declarations are much more 
"interesting" ;-)