From: Dave Harris (brangdon_at_[hidden])
Date: 2004-10-11 06:33:56
In-Reply-To: <ck8s5t$p2p$1_at_[hidden]>
nesotto_at_[hidden] (Thorsten Ottosen) wrote (abridged):
> could you post your real code along with reasons for putting a null
> into the tree and maybe some comments about the density of null's in
> the tree.
There is no reason to put a null in the tree. The density of nulls in the
tree should be zero. The code needs to be surrounded by a test, equivalent
to:
if (pDog != 0) {
pDog->walk_to( pTree );
assert( pDog->location() == pTree );
// ... more code assuming the dog's location.
}
My point is that using null_object does not enable you to avoid the "if"
statement. And further, having a walk_to() member which is valid for some
Dog subclasses and not others, is not really an improvement.
-- Dave Harris, Nottingham, UK