> To me, it's the difference between pulling the strings on a puppet (method calling) vs placing a request to a colleague (messaging). This is the way I think

> To me, it's the difference between pulling the strings on a puppet (method calling) vs placing a request to a colleague (messaging). This is the way I think about it as well, the more concise notion is ask don't tell. By don't tell I'm thinking of telling an object to change it's state directly. This distinction can be very, very subtle.