From: Erwin Abbott <erwin.abbott@...>
Date: 2007-06-10T16:56:27+09:00
Subject: Re: Overloading Array Subtraction operator

The - operator compares objects by their ID, so they aren't removed
unless they are instances of the same object. They may have the same
value, but be separate instances like this example. You can accomplish
what you want like this:

array1.select{|x| !array2.include? x}
# => [{:name=>"stan", :phone=>"hehe}]

Array#include? compares using == so they are compared by value, not by
their #object_id.

[:a, :b, :c].object_id # => 2711200
[:a, :b, :c].object_id # => 2690960 ... a new instance, same value

Regards,
Erwin