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Dynamic binding (or late binding or virtual binding) is name binding performed as the program is running. [2] An example of a static binding is a direct C function call: the function referenced by the identifier cannot change at runtime. An example of dynamic binding is dynamic dispatch, as in a C++ virtual method call.
Dynamic polymorphism is more flexible but slower—for example, dynamic polymorphism allows duck typing, and a dynamically linked library may operate on objects without knowing their full type. Static polymorphism typically occurs in ad hoc polymorphism and parametric polymorphism, whereas dynamic polymorphism is usual for subtype polymorphism.
The process of verifying and enforcing the constraints of types—type checking—may occur at compile time (a static check) or at run-time (a dynamic check). If a language specification requires its typing rules strongly, more or less allowing only those automatic type conversions that do not lose information, one can refer to the process as strongly typed; if not, as weakly typed.
Some languages, like Perl and Common Lisp, allow the programmer to choose static or dynamic scope when defining or redefining a variable. Examples of languages that use dynamic scope include Logo, Emacs Lisp, LaTeX and the shell languages bash, dash, and PowerShell. Dynamic scope is fairly easy to implement.
However, relying on dynamic name resolution in code is discouraged by the Python community. [1] [2] The feature also may be removed in a later version of Python.[3]Examples of languages that use static name resolution include C, C++, E, Erlang, Haskell, Java, Pascal, Scheme, and Smalltalk.
The purpose of dynamic dispatch is to defer the selection of an appropriate implementation until the run time type of a parameter (or multiple parameters) is known. Dynamic dispatch is different from late binding (also known as dynamic binding). Name binding associates a name with an operation. A polymorphic operation has several ...
C# introduced support for dynamic multimethods in version 4 [8] (April 2010) using the 'dynamic' keyword. The following example demonstrates multimethods. Like many other statically-typed languages, C# also supports static method overloading. [9] Microsoft expects that developers will choose static typing over dynamic typing in most scenarios. [10]
Java may be considered more strongly typed than Pascal as methods of evading the static type system in Java are controlled by the Java virtual machine's type system. C# and VB.NET are similar to Java in that respect, though they allow disabling of dynamic type checking by explicitly putting code segments in an "unsafe context".