Re: friend typename

From:
"Earl Purple" <earlpurple@gmail.com>
Newsgroups:
comp.std.c++
Date:
Thu, 8 Jun 2006 10:04:04 CST
Message-ID:
<1149776243.655392.205430@h76g2000cwa.googlegroups.com>
LuB wrote:

Is the following snippet legal syntax?

template<typename T>
class A
{
    // friend class T; <----- illegal per [7.1.5.3/2] (thank you
Kai-Uwe Bux)

    friend typename T; // compiles on msvc 2005, fails on g++ variants
(cygwin 3.3.3 and redhat 3.2.3)

    int intVal;
};


friend typename T; is not standard but some compilers have been
extended to allow it.

The workaround can be to derive T from A<T> and have the members of
A<T> that you want T to access as protected. The downside of that, of
course, is that your T is exposed to the implementation details of
A<T>, it being a template. T might access A<T> in its implementation
only. (Probably does). But you can always "pImpl" this anyway so the T
that derives from A<T> is a pImpl class (not really important if it
doesn't encapsulate, as you don't really have to encapsulate
encapsulations).

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