How to resolve "pure virtual method called"
By the time your destructor is called, the destructor of inherited classes has already been called. Within constructors and destructors, the dynamic type of the object can effectively be considered to be the same as the static type. That is, when you call virtual methods from within your constructors/destructors it's not the overriden versions of them that are called.
If SomePureVirtualMethod
needs to be called at the destructor, then you will have to call it within the destructor of the class where the actual definition of the method you want is.
When you call the virtual
method in the destructor of the Base class SomeClass
it calls the method(SomePureVirtualMethod()
) of the Base class SomeClass
which is a pure virtual method with no definition. And hence the error.
Why does this happen?
The type of this
in constructor or destructor is of the type whose constructor or destructor is being called and hence dynamic dispatch doesn't work in constructors and destructors as you would expect it to work in all other functions.
Why does it crash?
Because calling a pure virtual function from constructor or destructor is an Undefined Behavior.
C++03 10.4/6 states
"Member functions can be called from a constructor (or destructor) of an abstract class; the effect of making a virtual call (10.3) to a pure virtual function directly or indirectly for the object being created (or destroyed) from such a constructor (or destructor) is undefined."
How to avoid it?
Just ensure that you don't call a pure virtual function from constructor or destructor.
Don't call virtual
methods in constructor or destructor unless you understand the dynamics involved.