Editing Function object (section)

== Description ==
A typical use of a function object is in writing [[callback (computer science)|callback]] functions. A callback in [[procedural programming|procedural languages]], such as [[C (programming language)|C]], may be performed by using [[function pointer]]s.<ref>{{cite web
 | url        = http://progtutorials.tripod.com/cpp1.htm#_Toc50820124
 | title      = C++ Tutorial Part I - Basic: 5.10 Function pointers are mainly used to achieve call back technique, which will be discussed right after.
 | author     = Silan Liu
 | publisher  = TRIPOD: Programming Tutorials Copyright © Silan Liu 2002
 | quote      = Function pointers are mainly used to achieve call back technique, which will be discussed right after.
 | access-date = 2012-09-07
}}</ref> However it can be difficult or awkward to pass a state into or out of the callback function. This restriction also inhibits more dynamic behavior of the function. A function object solves those problems since the function is really a [[facade pattern|façade]] for a full object, carrying its own state.

Many modern (and some older) languages, e.g. [[C++]], [[Eiffel (programming language)|Eiffel]], [[Groovy (programming language)|Groovy]], [[Lisp (programming language)|Lisp]], [[Smalltalk]], [[Perl]], [[PHP]], [[Python (programming language)|Python]], [[Ruby (programming language)|Ruby]], [[Scala (programming language)|Scala]], and many others, support [[first-class function]] objects and may even make significant use of them.<ref>{{cite web
 | url        = http://progtutorials.tripod.com/cpp1.htm#_Toc50820124
 | title      = C++ Tutorial Part I - Basic: 5.10 Function pointers are mainly used to achieve call back technique, which will be discussed right after.
 | author     = Paweł Turlejski
 | date       = 2009-10-02
 | publisher  = Just a Few Lines
 | quote      = PHP 5.3, along with many other features, introduced closures. So now we can finally do all the cool stuff that Ruby / Groovy / Scala / any_modern_language guys can do, right? Well, we can, but we probably won’t… Here's why.
 | access-date = 2012-09-07
}}</ref> [[Functional programming]] languages additionally support [[closure (computer science)|closures]], i.e. first-class functions that can 'close over' variables in their surrounding environment at creation time. During compilation, a transformation known as [[lambda lifting]] converts the closures into function objects.