etc) Complex values are passed by reference. You'd have to use
something like StructCopy or Duplicate to make a copy if that's what you
wanted.
http://livedocs.macromedia.com/coldfusion/6.1/htmldocs/functa91.htm
Joe
-----Original Message-----
From: Michael Hodgdon [mailto:[EMAIL PROTECTED]
Sent: Wednesday, September 08, 2004 4:03 PM
To: CF-Talk
Subject: Re: reference in cfc
Hey Jim,
Thanks for getting back to me. Unfortunately it does make sense. I
really thought (and was hoping) that when you ask a function for some
data that it returns a copy of that data not a reference to that objects
data. What is the standard practice for this? How do you truly protect
an objects data from corruption if when you use a getter on it it
returns a reference pointer not a copy?
>No. not really.
>
>
>
>When you "var" a variable you do, indeed, make it private to the
function.
>However if you place a reference to a public object in a var'd variable
it's
>still a public object.
>
>
>
>In a sense the var keyword only affects the actual label of the
variable,
>not its contents. It does not make clones of its contents or anything
like
>that.
>
>
>
>The following is bad code, but (I hope!) should explain things:
>
>
>
><cfset foo = structnew() /> <!--- this creates a variable "foo" in the
>variables scope.
>
><cfset foo.fiddle = 3 />
>
>
>
><cffunction>
>
>
>
><cfset var foo = structnew() /> <!--- this creates a brand new
variable
>called "foo" completely unconnected with the one in the variables
scope.
>
>
>
></cffunction>
>
>
>
>
>
><cffunction>
>
>
>
><cfset var foo = variables.foo /> <!--- this creates a brand new
variable
>called "foo" completely unconnected with the one in the variables
scope.
>HOWEVER the value in this completely unconnected variable is a
reference to
>the variables.foo varialble. Changing foo.fiddle in the function
changes
>foo.fiddle in the referenced object.
>
>
>
></cffunction>
>
>
>
>
>
>Does that make sense or muddy things further?
>
>
>
>Jim Davis
>
>
>
>
>
>From: Michael Hodgdon [mailto:[EMAIL PROTECTED]
>Sent: Wednesday, September 08, 2004 3:05 PM
>To: CF-Talk
>Subject: reference in cfc
>
>
>
>Question for the list. It has to do with what appears to be object
>reference
>with data stored in a cfc. Any help you got would be great, oh yeah,
and
>kind
>of an emergency fo us! Coming up on a deadline fast!
>
>It is my understanding that when you "<cfset var var_myvar = "">" (var
out a
>
>variable) you capture information at a function level not at a
component
>level.
>Therefore if I have a data collection in a component that I want to
grab,
>analyze, edit, and send to the user without editing the original shared
>component version I can just grab it using the var scope. Once in the
var
>scope
>I can make my edits without affecting the original shared scope
version.
>Maybe
>a description will better explain this:
>
>Here is the code I am using to access and modify my component:
>
><!--- create and initialize the test object in local memory --->
><cfset variables.test = createObject("component",
"cf_components.test")>
><cfset variables.test.initializeObject()>
>
><!--- get and dump the data for this customer --->
><!--- you should see two keys "firstname" and "lastname" --->
><cfdump var="#variables.test.getCustData()#">
>
><!--- perform a customer analysis, this customer analysis should return
a
>structure with a new "description" key in it --->
><!--- Inside the function I have scooped the component level customer
>information by using a getter on the original shared data --->
><!--- Thre returnvariable dumps the data into the var scope. My edits
>should
>remain only in that vared out variable --->
><!--- with the "firstname", "lastname", and "description" field
contained in
>
>var_stCustomerData --->
><cfdump var="#variables.test.customerAnalysis()#">
>
><!--- get the customers original data. This data sits in the shared
scope
>of
>the test object and should not reflect the changes made in
customerAnalysis
>to
>the vared version --->
><!--- I should only see two keys "firstname" and "lastname" however the
edit
>
>performed in customerAnalysis (on the vared version of the data) edits
the
>original information putting description in the shared component
version
>--->
><cfdump var="#variables.test.getCustData()#">
>
>Here is my cfc:
><cfcomponent displayname="test" hint="I am a component that test
references
>to
>stored data.">
>
><cffunction name="initializeObject" hint="I prepare the object by
setting
>some
>intial data" access="public" output="no" returntype="boolean">
>
> <!--- Set up the customer object --->
> <cfscript>
>
> this.objName = "customer";
>
> // Set up the customer object data containers
> stCustomerInfo = structNew();
> stCustomerInfo.firstname = "michael";
> stCustomerInfo.lastname = "hodgdon";
>
> </cfscript>
>
> <cfreturn "1">
>
></cffunction>
>
><cffunction name="getCustData" hint="I return the customer data"
>access="public" output="no" returntype="struct">
>
> <cfreturn stCustomerInfo>
>
></cffunction>
>
><cffunction name="customerAnalysis" access="public" output="no"
>returntype="any">
>
> <cfset var var_stCustomerData = "">
>
>
> <!--- grab the customer data and place it in a local variable --->
> <cfinvoke
> method="getCustData"
> returnvariable="var_stCustomerData">
>
>
> <!--- if your name is michael --->
> <cfif var_stCustomerData.firstname EQ "michael">
>
> <!--- add to the temp local var a customer description --->
> <cfset structInsert(var_stCustomerData, "description", "Your name is
>mike")>
>
>
> <!--- your name is not michael --->
> <cfelse>
>
> <!--- add to the temp local var a customer description --->
> <cfset structInsert(var_stCustomerData, "description", "Your name is
not
>mike")>
>
> </cfif>
>
> <!--- return the edited customer information --->
> <cfreturn var_stCustomerData>
>
></cffunction>
>
></cfcomponent>
>
> _____
_____
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