== operator

[sksjava]

I have overloaded the "==" operator for a class. But now I want to only
compare the addresses of the objects, is there is a c++ mechanism to do this
without casting?

Ex:- (not compileable)
void whatever(Someth ing* one, Something* two) // "==" is overloaded for
class Something
{
// want to compare one's and two's addresses
if ( one == two ) {} // don't want to invoke the "==" operator

// only solution that I can think of
void* onev = reinterpret_cas t<void*>(one);
void* twov = reinterpret_cas t<void*>(two);
if ( onev == twov ) {}
}

[Victor Bazarov]

Re: == operator

"sksjava" <sksjava@hotmai l.com> wrote...[color=blue]
> I have overloaded the "==" operator for a class. But now I want to only
> compare the addresses of the objects, is there is a c++ mechanism to do[/color]
this[color=blue]
> without casting?
>
> Ex:- (not compileable)
> void whatever(Someth ing* one, Something* two) // "==" is overloaded for
> class Something
> {
> // want to compare one's and two's addresses
> if ( one == two ) {} // don't want to invoke the "==" operator
>
> // only solution that I can think of
> void* onev = reinterpret_cas t<void*>(one);
> void* twov = reinterpret_cas t<void*>(two);
> if ( onev == twov ) {}
> }[/color]

(a) You cannot change the default behaviour of comparing pointers (you
can call them addresses, but they are still pointers, a built-in
C++ type) because you cannot change the behaviour of the operators
for built-in types. E.G. you cannot overload operator+(int,i nt).

(b) Even though you cannot change it, why not simply rely on comparing
pointers provided to you by C++ already? What do you find not to
your liking in it?

(c) Any pointer-to-object can be converted to a pointer-to-void without
a cast (IOW, implicitly), so you can drop the casts from your code.

V

[Adam Fineman]

Re: == operator

sksjava wrote:[color=blue]
> I have overloaded the "==" operator for a class. But now I want to only
> compare the addresses of the objects, is there is a c++ mechanism to do this
> without casting?
>
> Ex:- (not compileable)
> void whatever(Someth ing* one, Something* two) // "==" is overloaded for
> class Something
> {
> // want to compare one's and two's addresses
> if ( one == two ) {} // don't want to invoke the "==" operator[/color]
<snip>

You don't have to do anything. When you compare two pointers, you are
already comparing addresses, not what they are pointing to.

Write yourself a small test program and prove this to yourself.

- Adam

--
Reverse domain name to reply.

[sksjava]

Re: == operator

"sksjava" <sksjava@hotmai l.com> wrote in message
news:bugsc7$2r2 $1@news.lsil.co m...[color=blue]
> I have overloaded the "==" operator for a class. But now I want to only
> compare the addresses of the objects, is there is a c++ mechanism to do[/color]
this[color=blue]
> without casting?
>
> Ex:- (not compileable)
> void whatever(Someth ing* one, Something* two) // "==" is overloaded for
> class Something
> {
> // want to compare one's and two's addresses
> if ( one == two ) {} // don't want to invoke the "==" operator
>
> // only solution that I can think of
> void* onev = reinterpret_cas t<void*>(one);
> void* twov = reinterpret_cas t<void*>(two);
> if ( onev == twov ) {}
> }
>
>[/color]

My apologies. I am not all there most of the time and even worse today. :-)