MACROMEDIA COLDFUSION MX 61-DEVELOPING COLDFUSION MX, Develop Manual

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Dynamic expressions and dynamic variables 95
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:
<cfoutput>#DE("1" & "2")#</cfoutput>
You might expect this line to display """1"" & ""2""". Instead, it displays “12”, because
ColdFusion processes the line as follows:
1
Evaluates the expression "1" & "2" as the string “12”.
2
Passes the string "12" (without the quotes) to the
DE
function.
3
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”.
About the Evaluate function
The
Evaluate
function takes one or more string expressions, dynamically evaluates their contents
as expressions from left to right, and returns the result of evaluating the rightmost argument.
The following example shows the
Evaluate
function and how it works with ColdFusion variable
processing:
<cfset myVar2="myVar">
<cfset myVar="27/9">
<cfoutput>
#myVar2#<br>
#myVar#<br>
#Evaluate("myVar2")#<br>
#Evaluate("myVar")#<br>
#Evaluate(myVar2)#<br>
#Evaluate(myVar)#<br>
</cfoutput>
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 98 .
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 97 .
Function Purpose