Re: An overloaded operator& needs the address of its argument

From:

=?iso-8859-1?q?Erik_Wikstr=F6m?= <eriwik@student.chalmers.se>

Newsgroups:

comp.lang.c++

Date:

9 May 2007 23:58:36 -0700

Message-ID:

<1178780316.433192.44600@u30g2000hsc.googlegroups.com>

On 10 Maj, 07:02, "Jim Langston" <tazmas...@rocketmail.com> wrote:

"Sylvester Hesp" <s.h...@oisyn.nl> wrote in message

news:4641d13c$0$322$e4fe514c@news.xs4all.nl...

"Angel Tsankov" <fn42...@fmi.uni-sofia.bg> wrote in message
news:f1siu4$ppu$1@aioe.org...

--
Angel Tsankov
fn42...@fmi.uni-sofia.bg
"Sylvester Hesp" <s.h...@oisyn.nl> wrote in message
news:4641bcac$0$336$e4fe514c@news.xs4all.nl...

"Angel Tsankov" <fn42...@fmi.uni-sofia.bg> wrote in message
news:f1sd1q$6jg$1@aioe.org...

How can an overloaded operator& take the address of its argument:

template<typename T>
Smth operator &(T& SomeObject)
{
// The address of SomeObject is needed here
}

It's argument is always 'this', as you can't define the unary & as a
non-member. And since 'this' is a pointer, you already have it's addr=

ess

Does the standard say that unary address-of operator must be a member?=

so, where?

You're absolutely right, I was mistaken.
You could take the address by using a reinterpret_cast to a primitive t=

ype

on which the unary & does what you want. boost::addressof does it like
that:

template<class T> T* addressof(T& t)
{
return reinterpret_cast<T*>(&const_cast<char&>(reinterpret_cast<const
volatile char&>(t)));
}

I must be missing something. Why wouldn't

template<class T> T* addressof(T& t)
{
return &*t;
}

work?

First you dereference t (which means that T must either be a pointer
of implement operator *) and then you take the address of what was
returned. So if T was a normal pointer then you would return a copy of
t right?

However since the return-type is T* this does not compile for normal
pointers, nor for builtin functions. The only thing I can see this
working for is something like this:

struct Foo {
Foo& operator*() {return *this;}
};

I think you must have forgotten something in your previous post.

--
Erik Wikstr=F6m