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Fun with Functions and CFCs II - Object Hacking, There Is No Privacy

posted under category: ColdFusion on December 11, 2007 at 1:00 am by Nathan

There are a lot of fun and interesting things you can do with ColdFusion components that languages like Java just don't let you. This is part 2 in my series to explore the interesting things that you can do with ColdFusion components and functions.

Before we begin, let's make a test CFC - here's the one I'm using; Test.cfc:
<cfcomponent>

  <cffunction name="init" access="public">
    <cfreturn this />
  </cffunction>

  <cffunction name="privateMethod" access="private">
    <cfreturn "This is a Private Method!" />
  </cffunction>

  <cffunction name="publicMethod" access="public">
    <cfreturn "This is a Public Method!" />
  </cffunction>

</cfcomponent>

Now we'll make an instance of it in a plain-jane .cfm file:
<cfset myCFC = createObject("component","Test").init()>

Now here comes the fun part. I want to get and execute the private method from the .cfm page. Not allowed, right? Not exactly. let's make a free-floating function in my .cfm file (this could be done with a cffunction tag, but I like the familiar script syntax):
<cfscript>
  function getCurrentVariables() {return variables;}
</cfscript>

If I call getCurrentVariables() now, it will return the current document's variables scope, which consists of a reference to that function and to my CFC instance's this scope, but what if I put that function onto my test CFC's public interface?

<cfset myCFC.getVariables = getCurrentVariables />

now, myCFC.getVariables() gives me the variables scope of the CFC! if I dump myCFC.getVariables(), I can see everything that's going on inside. Woah, now I can play with the internals all I want.

#myCFC.getVariables().privateMethod()# returns "This is a Private Method!"