Also...

    Observable.throw(Exception.new("woops!")).subscribe(Class.new(Observer) do
    [...]
    end.new)

http://rxrb.codeplex.com/SourceControl/latest#lib/Rx.rb (bottom)

Even if the method were named sanely and consistently `Observable::on_error`, I still don't want to write code like the above.

BTW, I don't see any class variables in the re-opened Enumerable module.