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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.
Since C++ does not support late binding, the virtual table in a C++ object cannot be modified at runtime, which limits the potential set of dispatch targets to a finite set chosen at compile time. Type overloading does not produce dynamic dispatch in C++ as the language considers the types of the message parameters part of the formal message name.
Function overloading differs from forms of polymorphism where the choice is made at runtime, e.g. through virtual functions, instead of statically. Example: Function overloading in C++
This is done by using traditional polymorphism while also casting the argument to dynamic. [3] The run-time binder will choose the appropriate method overload at run-time. This decision will take into consideration the run-time type of the object instance (polymorphism) as well as the run-time type of the argument.
In C++, using such purely abstract classes as interfaces works because C++ supports multiple inheritance. However, because many OOP languages do not support multiple inheritance, they often provide a separate interface mechanism. An example is the Java programming language.
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 .
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 computer programming, a virtual method table (VMT), virtual function table, virtual call table, dispatch table, vtable, or vftable is a mechanism used in a programming language to support dynamic dispatch (or run-time method binding).