ColdFusion 10 - Selectively Exposing ColdFusion Component Behaviors With Closures

<cfscript>
// NOTE: CFScript tag added purely for Gist color-coding. Remove!

component
	output="false"
	hint="I provide account related functionality"
	{


	// I return an initialized component.
	function init( Numeric startingBalance = 0 ){

		// Store the initial balance of the component.
		variables.balance = startingBalance;

		// Return this object reference.
		return( this );

	}


	// I credit the account the given amount (adding money to the
	// account balance).
	function credit( Numeric amount ){

		// Add money to the account.
		variables.balance += amount;

		// Return this object reference for method chaining.
		return( this );

	}


	// I debit the account the given amount (removing money from
	// the account balance).
	function debit( Numeric amount ){

		// Remove money from the account.
		variables.balance -= amount;

		// Return this object reference for method chaining.
		return( this );

	}


	// I get the current balance.
	function getBalance(){

		// Return the current balance amount.
		return( variables.balance );

	}


}

// NOTE: CFScript tag added purely for Gist color-coding. Remove!
</cfscript>

<cfscript>


	// I return a new object with only the given method names expsed
	// as behaviors on the resultant object.
	function exposeMethods( target, methods ){

		// Define the behavior that will be exposed. This method will
		// act as a proxy to the underlying behavior which will pass
		// the message onto the target component and return the value
		// returned from the target component.
		var behavior = function(){

			// Get the name of the function being invoked.
			var methodName = getFunctionCalledName();

			// Invoke the method on the taret object and return the
			// result to the calling context.
			return(
				invoke( target, methodName, arguments )
			);

		};

		// Create the object we are going to return.
		var proxy = {};

		// For each method name, expose the behavior through the
		// proxy object.
		arrayEach(
			methods,
			function( methodName ){

				// Expose the behavior.
				proxy[ methodName ] = behavior;

			}
		);

		// Return the new proxy object with exposed behaviors.
		return( proxy );

	}


	// ------------------------------------------------------ //
	// ------------------------------------------------------ //
	// ------------------------------------------------------ //
	// ------------------------------------------------------ //


	// Create a new account component instance.
	account = new Account( 100 );


	// Now, let's create a proxy to the given account component that
	// only exposes the credit and the balance methods but not the
	// debit method.
	goodAccount = exposeMethods(
		account,
		[ "credit", "getBalance" ]
	);


	writeOutput( "Account credited [50]. <br />" );

	// Credit the account.
	goodAccount.credit( 50 );


	// Now, I know this is going to fail, but for funzies, let's try
	// to call the non-exposed behavior - debit() - on the proxy.
	try {

		writeOutput( "Trying to debit()." );

		// Try to invoke the debit() method - a non-exposed behavior.
		goodAccount.debit( 25 );

	} catch( Any cfcatch ){

		writeOutput( " [ FAILED ] <br />" );

	}


	// Now, let's call the exposed behavior to get the balanace.
	writeOutput( "Balanace: " & goodAccount.getBalance() );


</cfscript>