Scorpio Wishlist Item

Posted By : Dan Wilson May 16, 2007 10:34 AM

One of the proper jewels of ColdFusion is the dynamic nature of the language. There is nothing I love more than replacing tons of boilerplate code with a few lines of dynamic CF!

One language feature that could be improved is the ability to dynamically call a method on a component. I find CFInvoke a bit unwieldy, syntactically annoying, and in my humble opinion, unnecessary.

Take the following example:

view plain print about

1<cfset UserPreferences = CreateObject("component",User).init() />
2<cfset WhichPreference = "Lunch" />
3<cfset WhichStyle = "Heavy">
4
5<cfinvoke component="UserPreferences" method="get#WhichPreference#" returnvariable="LunchForToday">
6 <cfinvokeargument name="Style" value="#WhichStyle#">
7</cfinvoke>

In the above example, we have a UserPreferences object, a variable for the specific class of preferences and an argument. The intent of the code is to run a method called 'getLunch' on the 'UserPreferences' component and pass 'Heavy' as an argument. (We don't want a simple salad today, boyos!)

We got the job done. Now let us look at a different approach:

view plain print about

1<cfset UserPreferences = CreateObject("component", User).init() />
2<cfset WhichPreference = "Lunch" />
3<cfset WhichStyle = "Heavy">
4
5<cfset LunchForToday = UserPreferences['get' & WhichPreference](WhichStyle) />

This code does the exact same thing. The final statement sets LunchForToday equal to UserPreferences.getLunch("Heavy"). To me, this is a lot more intuitive than the cfinvoke method shown above. This code relies on the runtime evaluation of the method and the arguments. Since the 'getLunch' method exists and the call is made at runtime, this is a very logical and valid way to get the job done.

The only problem is it doesn't seem to work. Based on my testing and conversations with Important Folks, this is simply an error in the ColdFusion language parser. I've it on good authority that it has been filed as a bug with the ColdFusion team. I've added it to the Wishlist Wiki for Scorpio and now put it here on this blog.

Does this make sense? Would others find this useful?

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