Question

I have a template, which adds a specific ability to a class:

template <Class ReceiverOfAbility>
class Able : public ReceiverOfAbility, SomeOtherClass
{
...
}

Then I have a standard tree-like inheritance:

class Base
{};

class Derived1 : public Base
{};

class Derived2 : public Derived1
{};

...

But somewhere in the tree there is a “backwards branch”

class Derived2WithAbility : public Able<Derived2>
{};

Suppose I have:

 Base* basePointer = new DerivedWithAbility;

How can I cast basePointer to SomeOtherClass at runtime? dynamic_cast does not work. The problem is that there will be a lot of derived classes and I do not know in forward where in the tree does the class inherit the ability. I would need to search in the tree for the place where the inheritance from Able occurs.

Any ideas?

EDIT:

I tried to

dynamic_cast<SomeOtherClass*>(dynamic_cast<Derived2WithAbility*>(basePointer))

But I get:

error: ‘SomeOtherClass’ is an inaccessible base of ‘Derived2WithAbility’

Any Idea why?

Answer 1

class Able : public ReceiverOfAbility, SomeOtherClass

SomeOtherClass is a private base class of Able<whatever>. For dynamic_cast to work (i.e. to be able to cast to SomeOtherClass successfully), it must be a public base.