In studying mixins vs. dependency injection, I often hear the phrase "the Ruby way." Often developers say something along the lines of Ruby lets you reopen classes and redefine methods means that you can easily "inject" new references into your code at test-time. (see #6 at http://weblog.jamisbuck.org/2007/7/29/net-ssh-revisited) But testing is not my main concern; my concern is class reuse. I wan