[tessro]

Also, you can't make a Ruby object falsy. So if you overload #nil? you get fun problems like:

    obj.nil? # => true
    !!obj    # => true

[zwp]

> can't make a Ruby object falsy

You can override ! (see http://www.rubyinside.com/rubys-unary-operators-and-how-to-r... from earlier this week) so !!obj can evaluate to false. But there is still this to solve:

    ruby-1.9.3-p0 :008 > obj ? true : false
     => true 
    ruby-1.9.3-p0 :009 > 

If only there was a #to_bool to override...

(For the record: yuck).