Re: friend class in template

From:

"Carl Daniel [VC++ MVP]" <cpdaniel_remove_this_and_nospam@mvps.org.nospam>

Newsgroups:

microsoft.public.vc.language

Date:

Tue, 29 Jul 2008 21:29:31 -0700

Message-ID:

<eturezf8IHA.5900@TK2MSFTNGP04.phx.gbl>

Daniel wrote:

This template takes 3 type parameters, the first of which is named
event_handler. The friend declaration attempts to declare the class
event_handler to be a friend of this class, presumably to allow the
class actually specified for the first template parameter to have
access to this class's internals.

Unfortunately, the friend declaration doesn't do what the author
apparently thought it would do (at least not on a conforming
compiler). This declaration names a namespace scoped class named
'event_handler' as a friend - the class actually bound to the formal
template parameter named 'event_handler' is not befriended, as I
suspect the author intended. Worse than that, it won't even compile
with a conforming compiler.

I don't see 'event_handler'. I only see 'event_handler_class' and
'class_event_handler'. Those are two distinct names. Am I missing
something?

No, I am! I missed the fact that class_event_handler and
event_handler_class (what awful names!) are both defined.

The friend declaration names the namespace scoped class
'class_event_handler' as a friend. As Igor suggests, it probably isn't
doing anything useful.

-cd