Search results
Results From The WOW.Com Content Network
Python allows operator overloading through the implementation of methods with special names. [48] For example, the addition (+) operator can be overloaded by implementing the method obj.__add__(self, other). Ruby allows operator overloading as syntactic sugar for simple method calls.
The previous section notwithstanding, there are other ways in which ad hoc polymorphism can work out. Consider for example the Smalltalk language. In Smalltalk, the overloading is done at run time, as the methods ("function implementation") for each overloaded message ("overloaded function") are resolved when they are about to be executed.
The same function name is used for more than one function definition in a particular module, class or namespace; The functions must have different type signatures, i.e. differ in the number or the types of their formal parameters (as in C++) or additionally in their return type (as in Ada).
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.
Thought dates = new Advice (); // Polymorphism dates. message (); // Prints "Warning: Dates in calendar are closer than they appear." When a subclass contains a method that overrides a method of the superclass, then that (superclass's) overridden method can be explicitly invoked from within a subclass's method by using the keyword super . [ 3 ] (
The following example demonstrates multimethods. Like many other statically-typed languages, C# also supports static method overloading. [9] Microsoft expects that developers will choose static typing over dynamic typing in most scenarios. [10] The 'dynamic' keyword supports interoperability with COM objects and dynamically-typed .NET languages.
The problem is that, while virtual functions are dispatched dynamically in C++, function overloading is done statically. The problem described above can be resolved by simulating double dispatch, for example by using a visitor pattern. Suppose the existing code is extended so that both SpaceShip and ApolloSpacecraft are given the function
For languages whose object systems support multiple dispatch, not only single dispatch, such as Common Lisp or C# via the Dynamic Language Runtime (DLR), implementation of the visitor pattern is greatly simplified (a.k.a. Dynamic Visitor) by allowing use of simple function overloading to cover all the cases being visited.