Closure (computer programming)

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 (see Subroutine) 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

• Free variables and bound variables
• Google Closure Tools
• Subroutine

External links

• Closure (computer programming)

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

• Closure @ Wikipedia