Search results
Results from the WOW.Com Content Network
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.
The identity function is a particularly extreme example, but many other functions also benefit from parametric polymorphism. For example, an a p p e n d {\displaystyle {\mathsf {append}}} function that concatenates two lists does not inspect the elements of the list, only the list structure itself.
When using polymorphism, one sometimes needs to create copies of objects by the base class pointer. A commonly used idiom for this is adding a virtual clone function that is defined in every derived class. The CRTP can be used to avoid having to duplicate that function or other similar functions in every derived class.
Template metaprogramming (TMP) is a metaprogramming technique in which templates are used by a compiler to generate temporary source code, which is merged by the compiler with the rest of the source code and then compiled. The output of these templates can include compile-time constants, data structures, and complete functions.
In computer science, dynamic dispatch is the process of selecting which implementation of a polymorphic operation (method or function) to call at run time.It is commonly employed in, and considered a prime characteristic of, object-oriented programming (OOP) languages and systems.
The type is defined as: ., where is a type variable.This means: is the type of all functions which take as input a type α and two expressions of type α, and produce as output an expression of type α (note that we consider to be right-associative.)
In most object-oriented systems, the concrete function that is called from a function call in the code depends on the dynamic type of a single object and therefore they are known as single dispatch calls, or simply virtual function calls. Dan Ingalls first described how to use double dispatching in Smalltalk, calling it multiple polymorphism. [1]
For this reason, calling virtual functions in constructors is generally discouraged. In C++, the "base" function is called. Specifically, the most derived function that is not more derived than the current constructor or destructor's class is called. [7]: §15.7.3 [8] [9] If that function is a pure virtual function, then undefined behavior occurs.