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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). [9] Function overloading is usually associated with statically-typed programming languages that enforce type checking in function calls. An overloaded function is a ...
C++ uses function overloading with various signatures. The practice of multiple inheritance requires consideration of the function signatures to avoid unpredictable results. Computer science theory, and the concept of polymorphism in particular, make much use of the concept of function signature.
Ad hoc polymorphism is a dispatch mechanism: control moving through one named function is dispatched to various other functions without having to specify the exact function being called. Overloading allows multiple functions taking different types to be defined with the same name; the compiler or interpreter automatically ensures that the right ...
Operator overloading does not change the expressive power of a language (with functions), as it can be emulated using function calls. For example, consider variables a, b and c of some user-defined type, such as matrices: a + b * c
A function that can evaluate to or be applied to values of different types is known as a polymorphic function. A data type that can appear to be of a generalized type (e.g., a list with elements of arbitrary type) is designated polymorphic data type like the generalized type from which such specializations are made.
Often the compiler selects the overload to call based on the type of the input arguments or it fails if the input arguments do not select an overload. Older and weakly-typed languages generally do not support overloading. Here is an example of overloading in C++, two functions Area that accept different types:
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
There are methods that a subclass cannot override. For example, in Java, a method that is declared final in the super class cannot be overridden. Methods that are declared private or static cannot be overridden either because they are implicitly final. It is also impossible for a class that is declared final to become a super class. [9]