Binding

From RubySpec

From ruby-doc, "Objects of class Binding encapsulate the execution context at some particular place in the code and retain this context for future use. The variables, methods, value of self, and possibly an iterator block that can be accessed in this context are all retained. Binding objects can be created using Kernel#binding, and are made available to the callback of Kernel#set_trace_func.

These binding objects can be passed as the second argument of the Kernel#eval method, establishing an environment for the evaluation. "

Example One(from ruby-doc):

  class Demo
    def initialize(n)
      @secret = n
    end
    def getBinding
      return binding()
    end
  end
  k1 = Demo.new(99)
  b1 = k1.getBinding
  k2 = Demo.new(-3)
  b2 = k2.getBinding
  eval("@secret", b1)   #=> 99
  eval("@secret", b2)   #=> -3
  eval("@secret")       #=> nil

Example Two(example of dup):

  irb(main):001:0> a = [1,2,3]
  => [1, 2, 3]
  irb(main):002:0> b = a.dup
  => [1, 2, 3]
  irb(main):003:0> b[0] = 'a'
  => "a"
  irb(main):004:0> b
  => ["a", 2, 3]
  irb(main):005:0> a
  => [1, 2, 3]