Re: When are compiler generated functions generated?

From:

Vladimir Marko <swelef@post.sk>

Newsgroups:

comp.lang.c++.moderated

Date:

Tue, 14 Aug 2007 12:53:47 CST

Message-ID:

<1187087221.939007.11800@b79g2000hse.googlegroups.com>

On Aug 14, 5:57 am, Andrew Shepherd <shepher...@hotmail.com> wrote:

Suppose I had this class:

class NonCopyable
{
private:
    NonCopyable(const NonCopyable&);
    NonCopyable& operator=(const NonCopyable&);

};

//////////////////////////////////////////////////////////
// BigClass.h

class BigClass : NonCopyable
{

private:
   typedef std::vector<Widget> VecWidget;
   typedef std::set<VecWidget> VecWidgetSet;
   typedef std::multi_map<DooDad, VecWidgetSet> OneReallyUglyMap;

   OneReallyUglyMap m_reallyUglyMap;};

/////////////////////////////////////////////////////////////////////////////

In my project, there are 100 .CPP files that include BigClass.h. As
the code indicates, the class is never copied.

Is the compiler going to go ahead and generate a copy constructor and
assignment operator, even though I don't want or need one?

The implicitly-declared copy constructor will be implicitly-defined
if you _use_ it, see 12.8/7. In your case, if it was defined the
definition according to 12.8/8 would be ill-formed due to inaccessible
copy constructor of the NonCopyable base class; thus you can be sure
it
will _not_ be defined. Similarly for the implicitly-declared
assignment
operator.

Regards,
Vladimir Marko

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