Re: Template conversion and default copy constructor

From:
"Matthias Hofmann" <hofmann@anvil-soft.com>
Newsgroups:
comp.lang.c++.moderated
Date:
24 Jul 2006 21:50:44 -0400
Message-ID:
<44c54289$0$24900$9b4e6d93@newsread4.arcor-online.net>

not to copy constructors, whose signature must be

  X ( X [const] [volatile] & )


Please read 12.8/3 again. It also says that a member function template

is

never instantiated to perform the copy of a class object to an object of
its class type, thus refering to copy constructors.


In your next reading of 12.8/3, please pay close attention to the example
that follows the explanation:

[12.8/3]
A declaration of a constructor for a class X is ill-formed if its first
parameter is of type (optionally cvqualified) X and either there are no
other parameters or else all other parameters have default arguments. A
member function template is never instantiated to perform the copy of a
class object to an object of its class type. [Example:

  struct S {
    template<typename T> S(T);
  };

  S f();

  void g() {
    S a( f() ); // does not instantiate member template
  }

?end example]

I guess it is pretty clear now, what the member template instantiation

issue

is about: the would-be-illformed-when-instantiated template is not
instantiated.


I think you are right and I was wrong. I read the second sentence of 12.8/3
out of context, but now I am convinced that it only refers to the ill-formed
constructor.

--
Matthias Hofmann
Anvil-Soft, CEO
http://www.anvil-soft.com - The Creators of Toilet Tycoon
http://www.anvil-soft.de - Die Macher des Klomanagers

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