Closure (computer programming)

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In programming languages, a closure (also lexical closure or function closure) is a technique for implementing lexically scoped name binding in languages with first-class functions.

Description

Operationally, a closure is a data structure storing a function together with an environment:

  • A mapping associating each free variable of the function (variables that are used locally, but defined in an enclosing scope)
  • With the value or storage location the name was bound to at the time the closure was created.

A closure -- unlike a plain function -- allows the function to access those captured variables through the closure's reference to them, even when the function is invoked outside their scope.

See also

External links

The term closure has many different uses in different fields. See: