Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!att!ulysses!andante!alice!shopiro
From: shopiro@alice.UUCP (Jonathan Shopiro)
Newsgroups: comp.lang.c++
Subject: Re: operator new() scoping
Summary: members hide global functions with the same names
Keywords: storage management garbage collection new delete private
Message-ID: <9472@alice.UUCP>
Date: 13 Jun 89 18:47:18 GMT
References: <1989Jun7.115321.22620@mntgfx.mentor.com>
Organization: AT&T Bell Laboratories, Murray Hill NJ
Lines: 60

In article <1989Jun7.115321.22620@mntgfx.mentor.com>, nmyers@mntgfx.mentor.com (Nathan Myers) writes:
> Providing arguments for operators new() and delete() is a major
> advance.  It offers more power than "this=" semantics, and allows
> smaller, faster code.  However,
> 
> ark@alice.UUCP (Andrew Koenig) writes
> > Operator new (and operator delete) obeys the same scope rules as any
> > other member function: if defined inside a class, operator new hides
> > any global operator new.  For example:
> > 
> > 	class T {
> > 	/* stuff */
> > 	public:
> > 		void* operator new(size_t, Memory_speed);
> > 	/* more stuff */
> > 	};
> > 
> > 	T* tp = new T;		// Error!
> > 
> > The use of `new T' is incorrect in this example because the member
> > operator new hides the global operator new, so no operator new
> > can be found for T that does not require a second argument.
> 
> This seems inconsistent to me.  Other overloaded functions don't
> hide their neighbors, why should operator new()?  The standard way
> to hide a global is to declare a member with the same name and arguments.
> Then, if I (as class T author) want to disallow ::operator new(size_t),
> I can declare a private one and not define it.

No.  If the name is the same, the function is hidden.  For example:

	void foo(int);
	struct S {
		void foo();
		void bar();
	};
	void S::bar()
	{
		foo(1);   // error: unexpected  1 argument for S::foo()
	}


m
o
r
e

s
i
l
l
i
n
e
s
s
-- 
		Jonathan Shopiro
		AT&T Bell Laboratories, Warren, NJ  07060-0908
		research!shopiro   (201) 580-4229