Re: Copy constructors

"Doug Harrison [MVP]" <>
Thu, 05 Jul 2007 12:21:29 -0500
On Thu, 5 Jul 2007 18:11:55 +0100, "David Webber"
<> wrote:

Can someone remind me of the rules by which a default copy constructor is

I have a peculiar situation: a class for which I want to *forbid* a copy
constructor of the form

(1) X::X( const X & );

but instead have something similar of the form

(2) X::X( const X&, const Y& );

I could write (1) and make sure it always ASSERTs, but, rather than do that,
is there any way I can make the compiler throw an error if I inadvertently
try to call such a thing?

Most classes I create include the following:

class X

   // Copyguard
   X(const X&);
   void operator=(const X&);

Declaring these functions prevents the compiler from supplying default
versions. Declaring them private turns most attempted usage into
compile-time errors. Not defining them guarantees a link-time error if X
itself or a friend tries to use them.

Doug Harrison
Visual C++ MVP

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