Anne van Kesteren wrote:
What do implementors and authors think of having more optional method arguments in the DOM where that makes sense?
I frankly think it's a bad idea. For UA-provided objects, it significantly increases the implementation complexity. Since the IDL used can't express optional arguments, the UA would need to either ad-hoc define the default values for them or have a long hardcoded list of optional things with some sort of automated system for checking against that list on method calls...
Even worse, it increases complexity for _anyone_ who wants to implement these interfaces. Right now, if I want to write a JS library that allows authors to, say, abstract away XMLHttpRequest differences between UAs, and I want to use DOM events to communicate with my callees, I would implement EventTarget and authors could just use patterns they already know to set up listeners for events they're interested in. If you start allowing optional args, then I have to deal with authors not passing in all the args, which means more code for me.
-Boris
