ecoding5

gistfile1.sh

$ ruby poodr.rb 
poodr.rb:20:in `prepare_trip': undefined method `each' for nil:NilClass (NoMethodError)
        from poodr.rb:6:in `block in prepare'
        from poodr.rb:5:in `each'
        from poodr.rb:5:in `prepare'
        from poodr.rb:54:in `<main>'

poodr.rb

class Trip
  attr_reader :bicycles, :customers, :vehicle

  def prepare(preparers)
    preparers.each do |preparer|
      preparer.prepare_trip(self)
    end
  end
end

# when every preparer is a Duck
# that responds to 'prepare trip'

class Mechanic
  def initialize(bicycle)
    @bicycle = bicycle
  end

  def prepare_trip(trip)
    trip.bicycles.each do |bicycle|
      prepare_bicycle(bicycle)
    end
  end

  def bicycles
    [1, 2]
  end

  def prepare_bicycle(bike)
    p 'mech'
  end
end

class TripCoordinator
  def prepare_trip(trip)
    buy_food(trip.customers)
  end

  # ...
end

class Driver
  def prepare_trip(trip)
    vehicle = trip.vehicle
    gas_up(vehicle)
    fill_water_tank(vehicle)
  end

  # ...
end

m = Mechanic.new(2)
t = Trip.new
t.prepare([m])