VAR scoping using structures

At this stage in the game of ColdFusion, it is common knowledge why you must var-scope all variables in your methods in order to protect your data.  In case this is something new to you, say you set a variable named “myVar” in method A.  Say you had a method B and in it you had another “myVar” with a different purpose.   Unless you declare your variables like this: <cfset var myVar = “something” />  that data is shared between both methods and can be overwritten.

So typically when you have a method you var-scope all your private variables including queries or anything else like this:

One thing I have never been fond of is that once this is done there is effectively no visible difference in your code between variables that are var scoped and variables that aren’t.  For example, let’s say I var-scope mVarA and don’t var-scope myVarB.  When I access them in the method they visibly appear to be in the same scope… like this:

Looking at this, there is no visible way to see which of those variables is var-scoped without looking at the top of your method to see what you have done.   Plus, as you add variables to your methods, that var-scoping area will grow and you can have a large section of protected declarations.  I have found a different way to approach this by var-scoping a structure named “private” at the top of my methods.  Then in my code I can simply use <cfset private.myVar = “” />.  For example, the code above would become:

By doing this, I no longer have to go var-scope each individual variable, plus the code becomes far more obvious as to which variables exist in that “private” scope.