prohibit creation of object copies

[Wolfgang Jeltsch]

Hello,

what is the best way to prevent the user of a class from making copies of
objects of this class? Making the copy constructor private is a solution but I'm
looking for a better one.

Thanks,
Wolfgang

[Ron Natalie]

"Wolfgang Jeltsch" <je*****@tu-cottbus.de> wrote in message news:3F**************@tu-cottbus.de...

Hello,

what is the best way to prevent the user of a class from making copies of
objects of this class? Making the copy constructor private is a solution but I'm
looking for a better one.

We make the copy constructor (and also frequently the assignment op) private
and we don't implement it. Not only does this give compile errors when you
try to make external copies, but (at least on our systems) link errors if you
try to make copies inside the class.

[Thomas Matthews]

Wolfgang Jeltsch wrote:

Hello,

what is the best way to prevent the user of a class from making copies
of objects of this class? Making the copy constructor private is a
solution but I'm looking for a better one.

Thanks,
Wolfgang

Search the web for "Singleton Design Pattern".
Also search this newsgroup and news:comp.object.

--
Thomas Matthews

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[Rolf Magnus]

Wolfgang Jeltsch wrote:

Hello,

what is the best way to prevent the user of a class from making copies
of objects of this class? Making the copy constructor private is a
solution but I'm looking for a better one.

Better in which regard? It's quite simple, does the job and is the usual
technique, so what could be done 'better'?

[Filipe Sousa]

Wolfgang Jeltsch wrote:

Hello,

what is the best way to prevent the user of a class from making copies of
objects of this class? Making the copy constructor private is a solution
but I'm looking for a better one.

Thanks,
Wolfgang

I find this more elegant

class NonCopyable
{
protected:
NonCopyable() {}

private:
NonCopyable( const NonCopyable& );
NonCopyable& operator=( const NonCopyable& );
};

class Derived : public NonCopyable {}

---
Filipe Sousa

[tom_usenet]

On Fri, 05 Sep 2003 13:09:27 +0100, Filipe Sousa
<fi*************@alunos.ipb.pt> wrote:

Wolfgang Jeltsch wrote:

Hello,

what is the best way to prevent the user of a class from making copies of
objects of this class? Making the copy constructor private is a solution
but I'm looking for a better one.

Thanks,
Wolfgang

I find this more elegant

class NonCopyable
{
protected:
NonCopyable() {}

private:
NonCopyable( const NonCopyable& );
NonCopyable& operator=( const NonCopyable& );
};

class Derived : public NonCopyable {}

Or, similarly,

#include <boost/utility.hpp>

class Derived: boost::noncopyable {};

Tom