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From: Pete Becker <petebecker@acm.org>
Subject: Re: Member functions of class templates
Date: 1997/12/15
Message-ID: <3493F4F7.97160081@acm.org>#1/1
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References: <199712111833.LAA15148@ncar.ucar.EDU> <34918c26.2428088350@nntp.americasttv.com>
X-Original-Date: Sun, 14 Dec 1997 10:02:15 -0500
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Stanley Friesen wrote:
> 
> On 11 Dec 1997 18:21:56 PST, Luddy Harrison <luddy@concmp.com> wrote:
> 
> >
> >Could someone familiar with the intent behind this wording give me an
> >example of this rule at work?  It seems to imply that if I write
> >
> >   template <class S> class T {
> >      public:
> >        int f(S*);
> >        int g();
> >   };
> >
> >that f is (implicitly) a function template, which I would interpret to
> >mean that more than one f can be instantiated from this declaration,
> >according to the argument types presented to f at a call.
> 
> Yes.

Well, not really. There is no template function f(S*) dangling out
there. You can only name it in the context of some class T<S>, which is
what determines the type of S:

template <class S> class T {
   public:
     int f(S);
};
int main()
{
T<int> ti;
ti.f(3);	// calls T<int>::f(int)
ti.f(3.0);	// calls T<int>::f(int)
}

The purpose of this rule is simplify the description of how member
functions of template classes work. There is, however, a mechanism for
creating member function templates:

template <class S> class T {
   public:
     template<class U> int f(U);
};

Now the argument to f() determines what gets instantiated:

int main()
{
T<int> ti;
ti.f(3);	// calls T<int>::f(int)
ti.f(3.0);	// calls T<int>::f(double)
}
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