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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.
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.
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.
Dynamic type enforcement often allows programs to run that would be invalid under static enforcement. In the context of static (compile-time) type systems, type safety usually involves (among other things) a guarantee that the eventual value of any expression will be a legitimate member of that expression's static type.
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".
Dynamic dispatch contrasts with static dispatch, in which the implementation of a polymorphic operation is selected at compile time. 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.
Classes and interfaces declared as static members of another class or interface are behaviorally top-level classes. [18] super Inheritance basically used to achieve dynamic binding or run-time polymorphism in java. Used to access members of a class inherited by the class in which it appears.
In computer programming, a static variable is a variable that has been allocated "statically", meaning that its lifetime (or "extent") is the entire run of the program. This is in contrast to shorter-lived automatic variables, whose storage is stack allocated and deallocated on the call stack; and in contrast to dynamically allocated objects, whose storage is allocated and deallocated in heap ...