Adam Wathan has a new post on his site about a different way of thinking he's coming around to about methods, affordances and abilities.

In one of my current projects, I needed to be able to broadcast email announcements to all of the users in the system. If you've read about enough patterns and principles, there's a decent chance you saw [the line allowing an Announcement to perform the "broadcast" operation] and immediately thought to yourself: "What?! An announcement shouldn't be able to broadcast itself!"

I used to think that too, but over the last few years I've started to think differently.

He talks about "do-er" classes that normally would take in something like an announcement and perform the operation to broadcast it. He suggests that this comes from a misunderstanding about the point of methods: abilities versus things you could do with an object. He goes on to give some examples of double standards with DateTime handling, the complexity it could introduce and how, despite it sounding like an immediate action, the "broadcast" method could just be deferring to a background queue anyway.