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The curiously recurring template pattern (CRTP) is an idiom, originally in C++, in which a class X derives from a class template instantiation using X itself as a template argument. [1] More generally it is known as F-bound polymorphism, and it is a form of F-bounded quantification.
The C++ examples in this section demonstrate the principle of using composition and interfaces to achieve code reuse and polymorphism. Due to the C++ language not having a dedicated keyword to declare interfaces, the following C++ example uses inheritance from a pure abstract base class.
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.
Examples are templates in C++, and generic programming in Fortran and other languages, in conjunction with function overloading (including operator overloading). Code is said to be monomorphised , with specific data types deduced and traced through the call graph , in order to instantiate specific versions of generic functions , and select ...
In other words, the sockets library uses type punning to implement a rudimentary form of polymorphism or inheritance. Often seen in the programming world is the use of "padded" data structures to allow for the storage of different kinds of values in what is effectively the same storage space.
The concept of the virtual function solves the following problem: In object-oriented programming, when a derived class inherits from a base class, an object of the derived class may be referred to via a pointer or reference of the base class type instead of the derived class type.
What you're describing is called inheritance, and polymorphism is a consequence of inheritance. All systems using inheritance are polymorphic, but not all polymorphic systems use inheritance (in Smalltalk you can use inheritance, but it's not necessary), or even have the concept of "class" (like Self or Javascript which are based on prototypes ...
[citation needed] Examples of strictly object-based languages – supporting an object feature but not inheritance or subtyping – are early versions of Ada, [2] Visual Basic 6 (VB6), and Fortran 90. Some classify prototype-based programming as object-based even though it supports inheritance and subtyping albeit not via a class concept.