Why do I need to use `b->A::DoSomething()` instead of `b->DoSomething()` when calling a method from a parent class in C ?

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C Overload Resolution for Scope Conflicts

The provided code snippet illustrates a common challenge in C overload resolution when two methods with the same name exist in different scopes. In this scenario, the compiler relies on the scope visibility rules to determine the applicable method.

Problem:

When invoking the DoSomething method on an instance of class B, why is it necessary to explicitly use b->A::DoSomething() instead of simply b->DoSomething()?

Answer:

The compiler defaults to considering the smallest possible name scope, and in this case, it only recognizes the DoSomething method defined in class B. Since the argument list does not match this method's signature, the compiler issues an error.

To resolve this scoping issue, there are two approaches:

Explicit Scope Resolution:

Explicitly specify the scope of the desired method using the syntax b->A::DoSomething(), which forces the compiler to recognize the method defined in class A.

Inheriting Scope:

Use the using directive to bring the desired method into the scope of the derived class. For instance:

<code class="cpp">class B : public A {
public:
    using A::DoSomething;
    // ...
}</code>

By using either of these methods, you can ensure that the compiler correctly resolves the overload and invokes the intended DoSomething method.

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