Generic Invocation Wrapper For Core ColdFusion Functions

I happen to love ColdFusion's CFInvoke and CFInvokeArgument tags. They allow user defined functions (UDF) and ColdFusion component functions to be dynamically invoked using variable values. They don't need to be used all that often; but, when the time comes, these two tags can really make life easy. When it comes to core ColdFusion functions, however, these two tags can't help us. Right now, if you want to execute core ColdFusion functions dynamically, you have to fall back on the Evaluate() method. Now, there's nothing wrong with Evaluate(); but, it is neither as easy to use nor is it as flexible as CFInvoke. As such, I wanted to create a component-based proxy to allow CFInvoke-based execution of core ColdFusion functions.

The idea is straightforward: it's still powered by the traditional Evaluate()-based approach; but, it is made generic through the use of ColdFusion's onMissingMethod() function. I have a single component, FunctionProxy.cfc, that has a single method, onMissingMethod(). The onMissingMethod() method contains the code that invokes the requested method using Evaluate(). And since onMissingMethod() will accept any method name thrown at it, it allows all core ColdFusion functions to be invoked by-proxy.

FunctionProxy.cfc

As you can see, the onMissingMethod() method is programmatically building a snippet of code in the form of:

Evaluate( "function( x, y, z, .... )" )

You'll notice, however, that I am not simply using the name of the target function; rather, I am using the function reference made available within the current page context. I am only doing this because I found out a while back that Image-based functions don't play well with Evaluate(). That might be an old bug, since fixed; but for now, until I re-test, I figured I'd rely on the more universally proven approach.

With this FunctionProxy.cfc ColdFusion component in place, we can now use CFInvoke and CFInvokeArgument to dynamically execute core ColdFusion functions. In the following demo, I am using three different proxy-approaches:

As you can see, FunctionProxy.cfc allows us to dynamically invoke core functions using both individually defined arguments (CFInvokeArgument) and a collection of arguments (ArgumentCollection). Because the core ColdFusion functions all rely on ordered arguments, you have to name the arguments using their invocation index. When we run the above code, we get the following output:

Random Value: 16

Random Value: 18

Random Value: 10

If you think the use cases for CFInvoke are few and far between, the use cases for dynamically executing core ColdFusion functions are even more rare. But, if you do need to use a more reflection-based approach to core function invocation, the ability to leverage CFInvoke on top of the core functions can be super useful. Ideally, what I'd like to see down the road is CFInvoke's functionality extended to include core ColdFusion functions.

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