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#!/usr/bin/env ruby

# http://www.ruby-doc.org/core-1.8.7/classes/Object.html#M000006 :

#

# obj.instance_exec(arg...) {|var...| block } => obj

#

# Executes the given block within the context of the receiver (obj).

# In order to set the context, the variable self is set to obj while

# the code is executing, giving the code access to obj‘s instance variables.

# Arguments are passed as block parameters.

class Classy

  def self.foo

    puts self

  end

  def bar

    puts self

  end

end

class Executioner

  def exec(&block)

    instance_exec &block

  end

end

exe = Executioner.new # => #<Executioner:0x007f8cb884d108>

exe.exec { puts self } # => #<Executioner:0x007f8cb884d108>

exe.exec &lambda { puts self } # => #<Executioner:0x007f8cb884d108>

exe.exec &Classy.method(:foo).clone # => Classy

exe.exec &Classy.new.method(:bar).clone # => #<Classy:0x007f8cb884ce10>