Editing ColdFusion Markup Language (section)

== ColdFusion Components (CFCs) ==
CFCs provide some (not all) of the typical features and functionality that are provided by [[object-oriented]] (OOP) languages.
To create a CFC:
:Create a file with a .CFC extension (this distinguishes CFCs from ColdFusion templates, which have a .CFM extension).
:Use four tags to create the components, define their functions and [[arguments]], and return a value.
::<cfcomponent>: Defines a CFC
::<cffunction>: Defines the functions (methods) within a CFC
::<cfargument>: Defines the arguments (parameters) that a function accepts
::<cfreturn>: Returns a value or result from a function
CFCs are plain CFML. Within a CFC any CFML tag, function, custom tag, other components, etc. may be used.

CFCs can be used in various ways. If a method contained in a CFC simply needs to be invoked, the <cfinvoke> tag will create an instance of the CFC, invoke the desired method, and then destroy the instance of the CFC. <cfinvoke> takes the name of the component (minus the .cfc extension) and the method to execute. To access any returned data, the RETURNVARIABLE attribute provides the name of a variable to contain whatever the function returns.
CFCs are created using four tags, saved as .CFC files, and invoked using the <cfinvoke> tag.<ref>Forta, Ben [https://web.archive.org/web/20100528103657/http://www.adobe.com/devnet/coldfusion/articles/intro_cfcs.html Using ColdFusion components]. adobe.com</ref>

In the example below, component temperature.cfc has a method FtoC which converts temperature from Fahrenheit to Celsius. The test.cfm template invokes the method and converts 212 degrees Fahrenheit and outputs the result.

<syntaxhighlight lang="cfm">
<!--- temperature.cfc --->
<cfcomponent>
  <cffunction name="FtoC" access="public" returntype="numeric">
    <cfargument name="fahrenheit" required="yes" type="numeric" />
    <cfset answer= (fahrenheit - 32)*100/180 />
    <cfreturn answer />
  </cffunction>
</cfcomponent>
<!--- test.cfm --->
<cfset fDegrees = 212 />
<cfinvoke component="temperature" method="FtoC" returnvariable="result">
  <cfinvokeargument name="fahrenheit" value="#fDegrees#" />
</cfinvoke>
<cfoutput>#fDegrees#&deg;F = #result#&deg;C</cfoutput> <br />
</syntaxhighlight>

CFCs may also be instantiated as objects. Assuming a CFC file called Person.cfc, an instance of this CFC would be instantiated as follows:
<syntaxhighlight lang="cfm">
<cfset person = CreateObject("component", "Person") /></syntaxhighlight>

CFCs also form the basis of the ability to create [[web services]] in CFML. A CFC is created in the usual way, and the attribute access="remote" added to any function within the CFC will make that function available to be called as a [[SOAP]]-based web service. The CFML engine auto-generates a [[Wsdl|WSDL]] and creates all the necessary stubs for the web service to function.