Re: Defining member function templates of class templates out of line

From:
greghe@pacbell.net (Greg Herlihy)
Newsgroups:
comp.std.c++
Date:
Fri, 25 May 2007 02:25:02 GMT
Message-ID:
<C27B6410.9C3E%greghe@pacbell.net>
On 5/24/07 12:39 PM, in article
1180001745.029006.204310@m36g2000hse.googlegroups.com, "Nicola Musatti"
<nicola.musatti@gmail.com> wrote:

Hallo,
14.5.2 (1) states that member function templates of class templates
may be defined outside of their class template definition. However it
only provides an example where the member function template has a
function parameter whose type matches the template parameter. No
explicit mention is made of whether such an out of line definition is
allowed when a member function's template arguments cannot be deduced
from function arguments.


According to the paragraph cited then, it is legal for any member function
template - including one with non-deducible template type parameters - to be
defined outside of its class definition.
  

In my opinion the following syntax should be allowed:

template <typename T> struct A {
    template <typename U> void f();
};

template <typename T> template <typename U>
void A<T>::f<U>() {
}


No, f<U> would signify some kind of specialization of the f<> member
template - and not its general definition. The correct definition of f()
would be:

     template <typename T> template <typename U>
     void A<T>::f() {
     }

This syntax is accepted by one out of the four compilers I tested.


It should not have been accepted by any C++ compiler.

Greg

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