How can I get the address of a virtual member function?

[Roy Yao]

Hello,

I need to pass a pointer to a
callback function to the lower
level modules. But the function
is thought to be a virtual member one.

How can I get the real address of
the virtual member function?

Best regards,
Roy

[Jerry Coffin]

Re: How can I get the address of a virtual member function?

In article <bl5cmu$1e5t$1@ mail.cn99.com>, flyao@263.net says...[color=blue]
> Hello,
>
> I need to pass a pointer to a
> callback function to the lower
> level modules. But the function
> is thought to be a virtual member one.
>
> How can I get the real address of
> the virtual member function?[/color]

The usual way to handle this depends on being able to pass a parameter
that will be passed back to the callback function when it gets called.
Assuming that's so (and it usually is) you typically use a static member
function as the callback function, and pass the address of the class as
the parameter:

class base {

virtual void callback() = 0;

static real_callback(v oid *v) {
static_cast<bas e *>(v)->callback();
}
};

class derived : public base {

virtual void callback() {
// whatever
}

OS_call_that_ca lls_back(static _cast<void *>(this));
};

--
Later,
Jerry.

The universe is a figment of its own imagination.