BlackBox : Overriding the 'as' operator

Overriding the 'as' operator

Warner Onstine — Thu, 06 Dec 2007 09:40:25 -0700

A friend of mine sent me a link to Charles Nutter’s blog on implementing interfaces using the as operator. While I was explaining how it worked to him I remembered that like many operators you can also override this one using asType(). This got us to thinking when would you use this functionality?

I have one project I’m working on right now (not ready to talk yet about as I want more code in place before I unveil it, :-P) but this might be useful. Say that you wanted to duck-type your object for specific class instances. Overriding as may be one place to do it.

When would this make sense? Personally I think something like this makes the most sense in a library that provides some kind of functionality to a bunch of classes (rather than a one-off case). But I’m curious to see how others have used this functionality, would help to shed some light on other uses I hadn’t thought of.

"Overriding the 'as' operator" by Warner Onstine

Fri, 07 Dec 2007 15:28:26 -0700

Very cool, just did a quick search on Krugle (yours is the only one that showed up).

So, what you're doing is creating three metaclasses for ArrayList, HashMap and String and then overriding the asType call through invokeMethod. Pretty slick.

"Overriding the 'as' operator" by Andres Almiray

Fri, 07 Dec 2007 00:29:32 -0700

Well for my part I use it on Json-lib to transform Strings, Lists and Maps to their JSON representation with a single coercion with as

http://json-lib.sourceforge.net/groovy.html