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The C++ examples in this section demonstrate the principle of using composition and interfaces to achieve code reuse and polymorphism. Due to the C++ language not having a dedicated keyword to declare interfaces, the following C++ example uses inheritance from a pure abstract base class.
In object-oriented programming, polymorphism more specifically refers to subtyping or subtype polymorphism, where a function can work with a specific interface and thus manipulate entities of different classes in a uniform manner. [61] For example, imagine a program has two shapes: a circle and a square. Both come from a common class called ...
Polymorphism can be distinguished by when the implementation is selected: statically (at compile time) or dynamically (at run time, typically via a virtual function). This is known respectively as static dispatch and dynamic dispatch, and the corresponding forms of polymorphism are accordingly called static polymorphism and dynamic polymorphism.
Polymorphism is the phenomenon wherein somewhat interchangeable objects each expose an operation of the same name but possibly differing in behavior. As an example, a File object and a Database object both have a StoreRecord method that can be used to write a personnel record to storage. Their implementations differ.
C++ does not have the keyword super that a subclass can use in Java to invoke the superclass version of a method that it wants to override. Instead, the name of the parent or base class is used followed by the scope resolution operator. For example, the following code presents two classes, the base class Rectangle, and the derived class Box.
Another example is C++ RTTI. More generally, most programming languages include mechanisms for dispatching over different 'kinds' of data, such as disjoint unions, runtime polymorphism, and variant types. Even when not interacting with type annotations or type checking, such mechanisms are materially similar to dynamic typing implementations.
Virtual functions allow a program to call methods that don't necessarily even exist at the moment the code is compiled. [citation needed] In C++, virtual methods are declared by prepending the virtual keyword to the function's declaration in the base class. This modifier is inherited by all implementations of that method in derived classes ...
Python creates a list of classes using the C3 linearization (or Method Resolution Order (MRO)) algorithm. That algorithm enforces two constraints: children precede their parents and if a class inherits from multiple classes, they are kept in the order specified in the tuple of base classes (however in this case, some classes high in the ...