2. SCOPE YOUR VARIABLE
 Always specify Scope of variables, this tells
coldfusion where to look for variable value and
gain performance.
 What’s different between #URL.firstname# and
#firstname#?
 Scope Evaluation Sequence
 Arguments
 Variables (local scope)
 CGI
 URL
 Form
 Cookie
 Client

3. Use Boolean evaluation
 Avoid IS, NOT IS where ever possible.
 <cfif arguments.firstName IS “”> equal to
<cfif len(arguments.firstName) eq 0> equal
to
<cfif len(arguments.firstName)>
 All above statement work same only
difference is performance.
 And this become remarkable on high traffic
sites.

4. AVOID IsDefine
 How do you check form.firstName variable exist or
not?
 Really simple <cfif isDefined(“form.firstName”)>
 Ever try <cfif structKeyExists(form,”firstName”)>?
 Second Method gives you almost double performance
gain.
 User structure function instead of isDefined to check
existence.
 Session, form, application, URL, arguments all are
structure variable. (Believe me)

5. AVOID Evaluate()
 Evaluate is Evil.
 Generally we use Evaluate function get
value from dynamic variables name.
 From.text1, form.text2, form.text3 can be
obtain with evaluate(“form.text” & k) where k
varies from 1 to 3.
 Wait we have another way to do so.
○ Form[“text” & k] (K varies from 1 to 3)
 Second method gives around 3-5 times
performance gain.

6. Use of CFOUTPUT
 I think CFOUTPUT is most common tag
use by Cfer and most widely use in
application.
 Beware unnecessary use of any tag, it
cost.
 Performance Gain 2 to 8 times
<cfloop from=“1” to=“10”
index=“I”>
<cfoutput>#i#</cfoutput>
</cfloop>
<cfoutput>
<cfloop from=“1” to=“10”
index=“I”>
#i#
</cfloop>
</cfoutput

7. AVOID over use of #
 # often use to output variable values.
 <cfoutput>#name#</cfoutput>
 Sometimes to use variable in string.
 <cfset a = “Hello #name#”>
 Other than this I don’t think # sign needed.
 Do not use in.
 <cfset #name# = “John”>
 <cfif #name# eq “John”>
 Will not fire any error but we have lots of other
thing to load ColdFusion.

8. Use cfqueryparam
 Always use cfqueryparam.
 You are adding big security loop hole if
you are avoiding it.
 It also boost up performance.

9. Best Practice for CFC
 In CFC allow access to data associated with CFC
only.
 Do not use invoke or creating component to calling
function from same CFC.
 Avoid use of this as it for variable scope.
 CFC is component and do not use it for presentation
layer (view).
 Always use output = “false” for function and on
component. In case you need it return as string
instead of printing output in CFC.
 Do not directly refer to external variables (variables,
session, Application). In some case application
variable is ok but never use session or variables.

10.  Specify arguments type in function
arguments to avoid unnecessary error and
it improve security.
 Specify return type of function wherever
possible.
Best Practice…
 Create structure variable LOCAL using var
declaration.
 Specify scope as LOCAL for all function’s
variables.
○ Give more readability.
○ Avoid variable overwrite

11. Keep in Mind
 Variables type array, string, number and
dates all pass by value.
 Variables type structure, query and other
complex variable pass by reference.

12. Things we already know
 Always give well defined name of
variables.
 Use camel case for variable name and
avoid underscore.
 Always write something meaning full
comments instead of making it horrible.
E.g. “Very complex logic, do not touch
this code”. 
 Use hint in cffunction and cfargument.