dkubb/equalizer — pull request #7 by dkubb (2012-12-24 09:04:56+00:00)
Title: Change #== to have stricter behaviour for subtypes

This change is in response to #5 where I think that equivalency should be made stricter, and more inline with the [Liskov Substitution Principle](http://en.wikipedia.org/wiki/Liskov_substitution_principle). It's not enough that the other object has equivalent state, it must be substitutable for the object the method `#==` is called on.

I realize this may be a stricter view than the standard ruby approach, where usage of `#==` is pretty ad-hoc. It is however consistent with how I've used it in the past with DataMapper and other oss projects.