In .NET can a class have virtual constructor?

Question

Can a class have virtual constructor??

If yes, why it is required?

Answer 1

No, how would it work? All constructors in the hierarchy have to be called when you derive child classes from base classes. Making a constructor virtual would imply otherwise.

Something that may be described as having virtual constructor like behaviour, is when you use the factory pattern. Imagine this scenario:

class AnimalFactory
{
    virtual Animal CreateAnimal( return new Animal("Cow"); );
}

The default behaviour of this factory is to create cows. But if we create a derived class:

class DogFactory : AnimnalFactory
{
    override Animal CreateAnimal( return new Animal("Dog"); );
}

We are now creating dogs. Of course this is not a true virtual constructor (which is impossible), this is virtual construction.