Should certain abstract classes be instantiable?

[Lionello Lunesu]

On 2-10-2009 8:32, Lionello Lunesu wrote:
> On 2-10-2009 4:30, Andrei Alexandrescu wrote:
>> Consider:
>>
>> class A {
>> abstract void fun() {}
>> }
>>
>> The class defines a function that is at the same time abstract (so it
>> requires overriding in derivees) and has implementation.
>>
>> Currently the compiler disallows creation of objects of type A, although
>> technically that is feasible given that A defines the abstract method.
>>
>> Should A be instantiable? What designs would that help or hinder?
>>
>>
>> Andrei
>
> If it were instantiable, what would be the difference between "abstract"
> and "virtual"?

OK, so I reread your post and yes, "it requires overriding in derivees."

Derived classes would still be allowed to do super.fun(), calling the 
'abstract' class's implementation. It's like NVI, only worse?

L.