mootoh (owner)

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gist: 166919 Download_button fork
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account.rb #
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# from Beautiful Code Sec 24, p.406 
#
require 'stm'
 
class Account
  def initialize
    @tvar = STM::TVar.new(0)
  end
 
  def withdraw(amount)
    balance = @tvar.read
    @tvar.write(balance - amount)
  end
 
  def deposit(amount)
    withdraw(amount)
  end
end
 
def transfer(from, to, amount)
   STM.atomically {
      from.withdraw(amount)
      to.deposit(amount)
   }
end