Proxy pattern in Ruby

gistfile1.rb

# -*- encoding: utf-8 -*-

class VirtualAccountProxy
  def initialize(&creation_block)
    @creation_block = creation_block
  end

  def deposit(amount)
    s = subject
    return s.deposit(amount)
  end

  def withdraw(amount)
    s = subject
    return s.withdraw(amount)
  end

  def balance
    s = subject
    return s.balance
  end

  def subject
    @subject || (@subject = @creation_block.call)
  end
end

class BankAccount
  def initialize(starting_balance)
    @balance = starting_balance
  end
  def method_missing(method_name, *args)
    p method_name
    p args
  end
end

proxy = VirtualAccountProxy.new do
  BankAccount.new(10)
end
proxy.withdraw(5)

# :withdraw
# [5]