virtual constructors

[katyusha]

why virtual destructors are possible but virtual constructors are not?

 

[WaterWalk]

why virtual destructors are possible but virtual constructors are not?

Virtual destructors are possible, because it's possible to delete a
pointer to base class. If virtual destructor is not used, it'll be
unknown what the pointer actually points: just a base class object or
a subobject of a derived class. If it's the latter case, then a
virtual destructor can guarantee that derived class destructor is
called.

But when a class is constructed, it is always clear which class to
construct. So there's no need to have virtual constructor. What's
more, virtual methods are mainly used to support polymorphism. In the
case of construction, polymorphism has no use.