Re: dynamic_cast is only casting right?
On Jun 3, 12:03 pm, Nick Keighley <nick_keighley_nos...@hotmail.com>
wrote:
On 3 June, 08:12, Stuart Redmann <DerTop...@web.de> wrote:
On 2 Jun., 16:24, "A" <a...@a.a> wrote:
in a function:
void Image_AssignImage(TObject *Sender)
{
dynamic_cast<TObjectDescendant *>(Sender)->DoWhatever();
}
in above function dynamic_cast is simply casting Tobject into compati=
ble
TObjectDescendant and then calls function DoWhatever contained in
TObjectDescendant (and not in Tobject)?
I'm not sure what "simply casting" means. Is it possible the actual
bit pattern may not chnage at all?
Yes, it is possible that the bit-pattern does not change when you do a
dynamic cast. It depends on the class hierarchy that the source object
is in.
For example, if there is only single inheritance, then chances are
that the bit pattern does not change in a dynamic_cast
To put it more clearly: It _tries_ to cast the _pointer_ to TObject
into a pointer to TObjectDescendant based on type information that is
attached to the TObject instance (note that you have to enable RTTI in
your compiler to make dynamic_cast work).
is it a valid implementation of C++ if it doesn't support RTTI?
No, but very few compilers are conforming in their default mode.
Bart v Ingen Schenau