[devoutsalsa]

The thing I don’t like about passing objects around is that the state inside the object is opaque, and debugging it can be extremely frustrating, especially in something like Ruby some people are way too liberal with magic for my taste. My personal preference is to see immutable data structures being passed around through reasonably named functions, and that the is usually good enough for me.

[nauticacom]

The thing I like about passing objects around is that the state inside the object is opaque :). Thus when changes to the internal details of Person happen, the behavior of which is depended on by Inbox and Message, as long as I have properly depended on its public behavior, I don't need to change anywhere else. If I was just using plain data values as is common in e.g. Clojure, every change to something's internal representation would require changes to places which depend on it.