Closures in ColdFusion: Structures/Collections

Railo 4 supports closures (a.k.a. anonymous functions) in ColdFusion.

I’ve been playing with the different ways of using them in the various apps I am building at Straker Translations.

Today there was a need to loop over the keys of a structure (a.k.a. associative arrays) and add the value of all the keys.

The usual idiom of regular ColdFusion code would be to use <cfloop> to go over all the keys and do the addition.

With Railo closures it is much simpler. Here is the code:

	<cfscript>
	// this is the collection we want to loop over and add all the keys
	numbers = { "num1" : 3, "num2" : 4}
	// setup a variable to hold the sum of the value of all the keys
	sum = 0
	// closure magic
	numbers.each( function(k,v){
	return sum+= v;
	})
	</cfscript>

view raw struct.cfm hosted with by GitHub

It is simple and elegant. Makes the code much more succinct and powerful.