ColdFusion 9 - Using LOCAL Scope

Question

I am starting to use the LOCAL scope in ColdFusion 9. I am trying to figure when to use it and when NOT to use it. Can you tell me the advantages/disadvantages of using the LOCAL scope either way? Should LOCAL be used on every page, or just in functions?

WHICH SHOULD BE USED?

<cfset ImageHeight = 36>  
<cfset ImageWidth = 42>  
<cfoutput>
<img src="" height="#ImageHeight#" width="#ImageWidth#">
</cfoutput>

OR

<cfset LOCAL.ImageHeight = 36>  
<cfset LOCAL.ImageWidth = 42>  
<cfoutput>
<img src="" height="#LOCAL.ImageHeight#" width="#LOCAL.ImageWidth#">
</cfoutput>

Answer 1

The local scope is defined only within functions.

function a() {
  //this way
  var myVariable = 0;
  //is the same as this way (in CF9)
  local.myVariable = 0;
}

Do not use the local scope outside functions.

Outside functions, variables default to the variables scope.

//this way
myVariable = 0;
//is the same as this way
variables.myVariable = 0;