User Guide

IsCustomFunction 529
IsCustomFunction
Description
Determines whether a name represents a custom function.
Returns
True, if name can be called as a custom function; False, otherwise.
Category
Decision functions
Function syntax
IsCustomFunction(name)
Parameters
Usage
The IsCustomFunction function returns true for any function that can be called as a custom
function, including functions defined using CFScript
function declarations and cffunction
tags, and functions that are ColdFusion component methods. For CFC methods, you must first
instantiate the component.
Note: To prevent undefined variable exceptions, always precede IsCustomFunction with an
IsDefined test, as shown in the example.
Example
<h3>IsCustomFunction Example</h3>
<cfscript>
function realUDF() {
return 1;
}
</cfscript>
<cfset X = 1>
<!--- Example that fails existence test --->
<cfif IsDefined("Foo") AND IsCustomFunction(Foo)>
Foo is a UDF.<br>
</cfif>
<!--- Example that passes existence test but fails IsCustomFunction --->
<cfif IsDefined("X") AND IsCustomFunction(X)>
X is a UDF.<br>
</cfif>
<!--- Example that passes both tests--->
<cfif IsDefined("realUDF") AND IsCustomFunction(realUDF)>
realUDF is a function.<br>
</cfif>
<!--- Example using a CFC, defined in TestCFC.cfc--->
<cfobject component="TestCFC" name="myTestCFCobject">
<CFIF IsDefined("myTestCFCobject.testFunc") AND
Parameter Description
name Name of a custom function. Must not be in quotes. If not a defined variable or
function name, ColdFusion generates an error.