Robert Klemme wrote: > Just for the sake of completeness: obj.kind_of? Customer is equivalent to > Customer === obj while obj.class == Customer has different semantics. The > latter form test for the exact class only while both former variants test > for classes and sub classes. ....and since testing for a specific class prohibits substituting in derived classes, and hence removes a lot of the power of dynamic OO programming, it's best to use kind_of? --unless you have a real need to check for only the precise class specified. And it's often better still to use respond_to? to check for the specific behaviors you need, and get the benefits of Duck Typing, rather than check for classes. mathew