Re: dynamic cast

From:
brangdon@ntlworld.com (Dave Harris)
Newsgroups:
comp.lang.c++.moderated
Date:
Tue, 25 Sep 2007 15:20:22 CST
Message-ID:
<memo.20070925200851.3532A@brangdon.cix.compulink.co.uk>
sarangbaheti@gmail.com (Sarang) wrote (abridged):

if( RTTI_is_subclass(ptr->GetClassType(),BaseObjectType) )
{
     BaseObject* basePtr = (BaseObject*)ptr;
}

Now the question is what are the benefits of using dynamic_cast here


Mostly checking? Dynamic_cast can handle more cases (eg involving
multiple inheritance), but possibly your RTTI module doesn't support them
anyway?

Personally I wouldn't like to mix C++'s RTTI with the home-grown module.
If I wanted to keep the module, I'd change its API to support something
like:

    if (BaseObject *basePtr = RTTI_dynamic_cast( ptr, BaseObjectType ))
    {
        // ...
    }

so neither C-Style cast nor dynamic_cast appeared in client code. Or else
abandon the RTTI module and just use the C++ mechanism:

    if (BaseObject *basePtr = dynamic_cast<BaseObjectType *>(ptr))
    {
        // ...
    }

which is a bit more concise.

-- Dave Harris, Nottingham, UK.

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