void pointer syntax

[H. S. Teoh]

On Mon, May 14, 2012 at 12:05:53PM -0700, H. S. Teoh wrote:
> On Mon, May 14, 2012 at 08:40:30PM +0200, Stephen Jones wrote:
> > I want an array of different classes of objects. I tried to
> > subsume the differences by extending the classes under a single
> > interface/abstract class/super class (3 different approaches) all
> > to no avail as I could not access the public variables of the
> > instantiated classes while storing them in an array defined by
> > the interface/super class.
[...]

Note also that while it's possible to downcast, being forced to downcast
is often a sign of bad OO design, cf. the Liskov substitution principle:

	http://en.wikipedia.org/wiki/Liskov_substitution_principle

If possible, one should always try to design the program in such a way
that downcasting is not necessary.

But, this being not an ideal world, downcasting is there for you to use
when you have to: cast(Derived) will return a reference to the derived
type if that particular object is actually an instance of Derived,
otherwise it returns null (so you're safe from accessing non-existent
members in an object that isn't actually an instance of Derived, which
may happen when you're using a base class reference to access the
object).


T

-- 
"Maybe" is a strange word.  When mom or dad says it it means "yes", but when my big brothers say it it means "no"! -- PJ jr.