Abstract functions in child classes

[Timon Gehr]

On 12/02/2011 05:05 PM, Adam wrote:
> To step back a bit, what is the *benefit* of not requiring a class
> to be declared abstract if it does not override an abstract member?
> It introduces implicit behavior and the potential for an additional
> test case (in *what* sane world should I even HAVE to test that
> something is instantiable?) for the sake of not typing 8 characters
> in a Class definition

A second possible use case:

class C(T): T{
     // some declarations
}

Now you really want that template to be instantiable with T being either 
an abstract or a concrete class. Anything else is bound to become 
extremely annoying.