Method overriding occurs when a subclass redefines a superclass method with the same signature. Virtual inheritance in C++ is an example. Some methods can be prevented from being overridden with keywords like “final” in Java and “const” in C++. Overriding is useful when adding functionality to a superclass method or completely redoing it for a specific object. Proper commenting is important to clarify the differences between superclass and subclass methods.
Method overriding is used in object-oriented programming within an inheritance hierarchy and occurs when a method defined in a superclass is redefined in a subclass. Usually, the subclass method does something different from the superclass method or expands on a superclass capability, but that doesn’t have to be the case. Method overriding occurs whenever a superclass method is redefined in a subclass, regardless of the contents of the redefined method. The redefined method signatures must be exactly the same.
For example, a class A might contain a method called “doSomething” and this method takes no input parameters. Also, classes B and C could be subclasses of class A. Class B could contain a method called “doSomething”, which takes no input parameters, and class C could contain a method “doSomething” which takes a number as a parameter of inputs. In this example, only class B would demonstrate the method override, because its “doSomething” method has the same method signature as its superclass, class A. The “doSomething” method in class C, on the other hand, demonstrates method overload because it creates a completely new method.
Virtual inheritance in C++ is another example of method overriding. Virtual methods in superclasses may or may not be implemented, but any subclass definition of them is an instance of a method override. When a method is overridden in a subclass, the superclass method is not called unless explicitly invoked. This specific way of calling an overridden method is often said to “hide” the superclass implementation.
While method overriding is very flexible, not all methods can be overridden, and there are times when this rigidity might be preferable. In both Java and C++, specific keywords can be applied in method signatures to prevent a method from being overridden in a subclass. To do this, Java uses the “final” keyword and C++ uses the “const” keyword. Method override prevention can be useful if a particular function must always be unchanged in an inheritance tree.
In general, you don’t need to override simple methods that get small chunks of data. The cases that tend to benefit the most from overriding are when a subclass aims to add functionality to a method of the superclass without creating an entirely new method to do so. Unusual cases where a method needs to be completely redone for a specific type of object could also benefit from this technique. Whenever a method is overridden, it is important for the programmer to properly comment both superclass and subclass methods. Ideally, these comments should clarify what each method variant does, as well as how and why they differ.
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