User Guide

Table Of Contents

Dynamic expressions and dynamic variables 87

Using dynamic evaluation

The following sections describe how to use dynamic evaluation and create dynamic expressions.

ColdFusion dynamic evaluation functions

The following table describes the functions that perform dynamic evaluation and are useful in

evaluating dynamic expressions:

Function argument evaluation considerations

It is important to remember that ColdFusion always evaluates function arguments before the

argument values are passed to a function:

For example, consider the following

DE function:

You might expect this line to display """1"" & ""2""". Instead, it displays “12”, because

ColdFusion processes the line as follows:

Evaluates the expression "1" & "2" as the string “12”.

Passes the string "12" (without the quotation marks) to the DE function.

Calls the DE function, which adds literal quotation marks around the 12.

Similarly, if you use the expression DE(1 + 2), ColdFusion evaluates 1 + 2 as the integer 3 and

passes it to the function. The function converts it to a string and surrounds the string in literal

quotation marks: “3”.

Function Purpose

DE Escapes any double-quotation marks in the argument and wraps the result in

double-quotation marks. The

DE function is particularly useful with the IIF

function, to prevent the function from evaluating a string to be output.

For an example of using the

DE function with the IIF function, see “Using the IIF

function” on page 90.

Evaluate Takes one or more string expressions and dynamically evaluates their contents

as expressions from left to right. (The results of an evaluation to the left can have

meaning in an expression to the right.) Returns the result of evaluating the

rightmost argument.

For more information on this function see “About the Evaluate function”

on page 88.

IIf Evaluates a boolean condition expression. Depending on whether this

expression is True or False, dynamically evaluates one of two string expressions

and returns the result of the evaluation. The

IIF function is convenient for

incorporating a

cfif tag in-line in HTML.

For an example of using this function, see “Using the IIF function” on page 90.

SetVariable Sets a variable identified by the first argument to the value specified by the

second argument. This function is no longer required in well-formed ColdFusion

pages; see “SetVariable function considerations” on page 90.