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When the program calls StoreRecord on the object, something needs to choose which behavior gets enacted. If one thinks of OOP as sending messages to objects, then in this example the program sends a StoreRecord message to an object of unknown type, leaving it to the run-time support system to dispatch the message to the right object. The object ...
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 ...
Roberts (p. 171) gives a related example in Java, using a Class to represent a stack frame. The example given is a solution to the Tower of Hanoi problem wherein a stack simulates polymorphic recursion with a beginning, temporary and ending nested stack substitution structure. [5]
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.
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.
In computer programming, operator overloading, sometimes termed operator ad hoc polymorphism, is a specific case of polymorphism, where different operators have different implementations depending on their arguments. Operator overloading is generally defined by a programming language, a programmer, or both.
Impredicative polymorphism (also called first-class polymorphism) is the most powerful form of parametric polymorphism. [1]: 340 In formal logic, a definition is said to be impredicative if it is self-referential; in type theory, it refers to the ability for a type to be in the domain of a quantifier it contains. This allows the instantiation ...
In programming language theory, subtyping (also called subtype polymorphism or inclusion polymorphism) is a form of type polymorphism.A subtype is a datatype that is related to another datatype (the supertype) by some notion of substitutability, meaning that program elements (typically subroutines or functions), written to operate on elements of the supertype, can also operate on elements of ...