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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).
The implementation in the subclass overrides (replaces) the implementation in the superclass by providing a method that has same name, same parameters or signature, and same return type as the method in the parent class. [2] The version of a method that is executed will be determined by the object that is used to invoke it. If an object of a ...
It is a form of method dispatch, which describes how a language or environment will select which implementation of a method or function to use. [1] Examples are templates in C++, and generic programming in Fortran and other languages, in conjunction with function overloading (including operator overloading).
And even if methods owned by the base class call the virtual method, they will instead be calling the derived method. Overloading occurs when two or more methods in one class have the same method name but different parameters. Overriding means having two methods with the same method name and parameters. Overloading is also referred to as ...
Rather, the derived class only needs to implement (override) the methods having different behavior than the base class methods. This can require significantly less programming effort if the base class contains many methods providing default behavior and only a few of them need to be overridden within the derived class.
The "vtable" method developed in C++ and other early OO languages (where each class has an array of function pointers corresponding to that class's virtual functions) is nearly as fast as a static method call, requiring O(1) overhead and only one additional memory lookup even in the un-optimized case. However, the vtable method uses the ...
Return types and thrown exceptions are not considered to be a part of the method signature, nor are the names of parameters; they are ignored by the compiler for checking method uniqueness. The method signatures help distinguish overloaded methods (methods with the same name) in a class. Return types are not included in overloading.
Here, attempting to use a non-class type in a qualified name (T::foo) results in a deduction failure for f<int> because int has no nested type named foo, but the program is well-formed because a valid function remains in the set of candidate functions.