Why Use Pure Virtual Destructors in C Abstract Classes?

Pure Virtual Destructors and Abstract Classes in C

Virtual destructors play a crucial role in managing memory in C when dealing with polymorphic relationships. However, the purpose of a pure virtual destructor raises questions, especially in relation to abstract classes.

1. When is a Destructor Made Pure Virtual?

A pure virtual destructor does not have an implementation in the base class, making it impossible to instantiate objects of that class. It's typically used when you want to force all derived classes to provide their own implementation of the destructor.

However, there's no practical reason for using a pure virtual destructor. The compiler will generate an implicit destructor for derived classes if the author does not provide one, making the pure virtual destructor in the base class irrelevant for the derived classes.

2. Good Practice for Abstract Classes and Destructors

It's not considered a good practice to make the destructor pure virtual in abstract classes. A virtual but non-pure destructor is sufficient to mark a class as abstract.

However, there may be a conceivable reason for using a pure virtual destructor in an abstract class: to serve as a reminder for derived classes to implement specific clean-up code. But this approach is not widely adopted.

Note: Even though a destructor is pure virtual, it requires an implementation in the base class to allow the instantiation of derived classes.

In summary, while pure virtual destructors are permitted in C , there's no practical need for them. When working with abstract classes, a non-pure virtual destructor is sufficient to ensure that derived classes have their own destructor implementations.

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