` `initialize'：未定义的方法` `gauge‘(NoMethodError)

Question

谁知道为什么我会收到这个错误：initialize': undefined methodgauge‘for # (NoMethodError)?！我的意思是，我正在使用attr_accessor作为gauge的getters和setters，但它仍然说我没有声明它。我在下面发布了一段代码。提前谢谢。

class ParkingLotGuest < Guest

attr_accessor :gauge, :electricity_bill, :type_of_stay  

def initialize (name, address, phone, arrival, lives_where, type_of_stay, guest_wishes_electricity)
    super(name, address, phone, arrival, lives_where)
    @type_of_stay = type_of_stay
    @electricity_bill = 0 
    @gauge = 0;
    if (guest_wishes_electricity[0,1] == "j")
        @gauge = lives_where.gauge
    end
end

下面是parking_lot类的代码：

class Parking_Lot

attr_accessor :nr
    attr_accessor :gauge
attr_reader :electricity_meter

# Initiates a new caravan plot with the number nr and a electricity meter between
# 2000 och 4000.
def initialize (nr)
    @nr = nr
            @gauge = gauge
    @electricity_meter = 4000-rand(2000)
end

# increases the electricity meter for use with a random amount between 
# 10-80 kWh per 24 h.
def increase_meter(days)
    generatedUse = (10+rand(70))*days
    puts "Increases the meter with " + generatedUse.to_s + " kWh."
    @electricity_meter += generatedUse
end

# Returns a string representation of the camping plot.
def to_s

  "Plot #{@nr+1} Electricity meter: #{@electricity_meter} kWh"

end 
end

露营类中的代码。

@staticGuests = Array[   
    ParkingLotGuest.new("Logan Howlett", "Tokyo", "07484822", 1, @parking_lots[0], "Husvagn", "j", @gauge), 
    ParkingLotGuest.new("Scott Summers",    "Chicago", "8908332", 2, @parking_lots[1], "Husbil", "j", @gauge),
  ParkingLotGuest.new("Hank Moody",     "Boston", "908490590",23, @parking_lots[2], "Tält", "n", @gauge),
  CabinGuest.new("Jean Grey", "Detroit", "48058221", 4, @parking_lots[3]['Wolverine']),
  CabinGuest.new("Charles Xavier",  "Washington DC", "019204822", 5, @parking_lots[4]['Thanos'])
]                                                                                                                      

Answer 1

更仔细地查看错误：

undefined method `gauge' for #<Parking_Lot:0x10017c860 @electricity_meter=3622, @nr=0> (NoMethodError) 

这就是说，Parking_Lot的一个实例收到了一个名为gauge的方法的方法调用，但它没有gauge方法。

在这一行中，只有一个方法调用。

@gauge = lives_where.gauge

@gauge = ...直接赋值给实例变量@gauge，绕过了setter方法，所以不是这样的。

lives_where.gauge可能就是人们所抱怨的。lives_where是Parking_Lot吗？