On Thu, 01 Dec 2011 12:58:24 -0500, Regan Heath <re...@netmail.co.nz>
wrote:
On Thu, 01 Dec 2011 17:50:48 -0000, Adam <a...@anizi.com> wrote:
Ok, starting to feel like I'm missing something obvious...
This:
void main() {
Child child = new Child;
}
also produces the (expected) error. Basically dmd was letting you get
away with the abstract class because you never instantiated it.
Child child;
is just a reference to a Child class.
You could argue the compiler should error in either case, in fact, I
would. But perhaps there is a good generic programming reason not to...
someone more experienced might be able to shed some light on it.
A Child reference could be for a further derived GrandChild type that does
actually implement the required functions. In fact, Child is also
abstract, it just isn't required to be marked as such.
All marking a class as abstract does is make it uninstantiable, just like
having an abstract method does. However, you can mark a class abstract to
prevent it from being instantiated, even when none of its methods are
abstract (could be useful in some situations).
However, I have no idea why you'd mark a concrete function as abstract.
That seems like a "just because we could" feature.
-Steve
