Variables in CFML; Overview of CFML Scopes

What follows is a quick reference to important information about each of the scopes defined in CFML. These scopes will be fully explained in the following pages.

Scopes Accessible as Structures

In CFMX all named scopes are available as structures. In CF 4.5 and 5.0 all named scopes with the exception of the Variable, Caller, Client, and Server scopes are available as structures.

This means that all of the CFML structure functions may be used to manipulate these scopes. In CF 5.0 and above the <CFDUMP> may be used to output the entire contents of any of these scopes.

Quick Reference Chart

Unless otherwise noted al of the following scopes are available in ColdFusion versions 4 and above.

Scope Prefix	Locking Required?	Can accept Complex Data Types?	Internet Standard?	Prefix Required to Access?
Transient Variable Scopes
Variables
CGI
URL
Form
Request*
Persistent Variable Scopes
Cookie
Client
Server
Application
Session
Extension Scopes (Custom Tags)
Attributes
Caller
ThisTag
Extension Scopes (Components/Functions)
Arguments**
This***
Function Local**

* Introduced in CF 4.5
** Introduced in CF 5.0
*** Introduced in CFMX

Other Scopes

ColdFusion provides many other special-purpose scopes. Most of these are specific to certain CFML tags and represent information concerning an instance of that tag. CFERROR, CFFILE, CFHTTP, CFCATCH and many other tags all return such dedicated variable scopes. These specialized scopes are generally read-only and only applicable to development with the tags that produce them. Because of this they will not be detailed in this guide.