Path: utzoo!attcan!uunet!zephyr.ens.tek.com!uw-beaver!ssc-vax!uvicctr.UVic.CA!mjunkin
From: mjunkin@uvicctr.UVic.CA.UUCP (Michael Junkin)
Newsgroups: comp.lang.c++
Subject: C++ and operator new()
Message-ID: <1155@uvicctr.UVic.CA.UUCP>
Date: 10 Jul 90 16:44:58 GMT
Reply-To: mjunkin@uvicctr.UUCP (Michael Junkin)
Organization: University of Victoria, Victoria B.C. Canada
Lines: 71


Hello:
    I'm having a bit of trouble with operator new. Specifically, I have a 
class X for which I often (but not always) want to allocate storage myself 
but sometimes want to use the builtin operator new. Thus, the class X contains
the definition

    static void *operator new(size_t);

The intent is that

    X *x = new X(...);		(1)

can be used to allocate and construct local objects while

    X *x = ::new X(...);	(2)

is used to allocate and construct global objects of class X.
    However, this does not work. The C code generated by both the AT&T
and SUN version 2.0 compilers is the same in both case 1 and case 2. As
an example the program

// *********************************

#include <stddef.h>
#include <iostream.h>

class X {
	int i;
    public:

  	X(int n) { i = n; }
	static void *operator new(size_t);
	static void operator delete(void *) {}
};

void *X::operator new(size_t n) 
{ 
    cout << "allocating locally\n";
    return new char[n];
}

main()
{
    X *x1 = ::new X(1);
    X *x2 = new X(2);
}

// *********************************

when compiled and run produces the output

allocating locally
allocating locally

Have I missed something, or is this a C++ compiler bug? I would appreciate any 
information on this matter.

Thanks in advance,
Michael.
-- 
------------------------------------------------------------------------
    *standard disclaimers apply*

    Michael D. Junkin
    Department of Computer Science
    University of Victoria
    Victoria, B.C.
    CANADA

    mjunkin@csr.UVic.ca (internet)