Re: why are all templated copy-constructors necessary?

From:
"Victor Bazarov" <v.Abazarov@comAcast.net>
Newsgroups:
comp.lang.c++
Date:
Tue, 3 Jul 2007 17:51:28 -0400
Message-ID:
<f6egd2$75k$1@news.datemas.de>
Alf P. Steinbach wrote:

* Victor Bazarov:

Claudius wrote:

Hello,

in my class TopTen I need to define three constructors while only
the last one, the most general in terms of templates, should be
sufficient in my opinion:

template <typename Tnum, short Trank, bool Tcont>
TopTen<Tnum,Trank,Tcont>::TopTen( const TopTen<Tnum,Trank,Tcont> &
tten );


As I understand it, the above is the actual copy constructor.


Uh... A templated constructor is never a copy constructor.


Correct. But are you sure what you're looking at *is* a templated
constructor?

You're confusing a templated constructor and a constructor in a class
template. Consider

    template<class T> struct A {
        A() {}
        A(A const& a); // non-templated copy constructor.
    };

    template<class S> struct B {
        B() {}
        template<class T> B(B<T> const& b); // templated constructor
    };

    // now the definitions
    template<class T> A<T>::A(A<T> const&) {}
    template<class S> template<class T> B<S>::B(B<T> const&) {}

    int main() { A<int> ai, aii(ai); B<int> bi; B<double> bd(bi); }

Now, which one looks more like the definition you tried correcting
me about?

 As you
implicitly state below:

[snip]


V
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