訪問對象屬性的同一屬性循環的結果[python]的

Question

使用for循環，我想追加字典的一個對象的屬性：

do = direct_objects[0].point_logs 
for direct_object in direct_objects: #Contains two objects 
      print (do is direct_object.point_logs) #Gives true both times 
      do = direct_object.point_logs 
      print(direct_object.id) #objects are different instances 
      dates = generate_dates_interval('2017-01-01', '2017-04-01', 14) #Generates dates with an interval of 14 days for the given period 

      for i in range(0, len(dates)-1): 

       point_logs, interval_logs, cum_logs = get_point_logs(direct_object, dates[i], 
                    dates[i+1]) # gets logs for given period 

       if point_logs is not None: 
        direct_object.point_logs.append(point_logs) 
       if interval_logs is not None: 
        direct_object.interval_logs.append(interval_logs) 
       if cum_logs is not None: 
        direct_object.cum_logs.append(cum_logs) 

我想通過日期循環和追加所有記錄到DirectObject的實例point_logs。然而，我得到的是，不是兩個獨立的列表，direct_object.point_logs成爲兩個直接對象的所有點日誌的大列表。

class DirectObject(object): 
    def __init__(self, id, created_date, deleted_date, name, type, point_logs = [], interval_logs = [], cum_logs= [], 
       services = None): 
     self.id = id 
     self.created_date = created_date 
     self.deleted_date = deleted_date 
     self.name = name 
     self.type = type 
     self.point_logs = point_logs 
     self.interval_logs = interval_logs 
     self.cum_logs = cum_logs 
     self.services = services 

    def __str__(self): 
     return str(self.name) + " id: " + str(self.id) + " type: " + str(self.type) 
    def __repr__(self): 
     return str(self.name) + " id: " + str(self.id) + " type: " + str(self.type) 

這是怎麼發生的？

Answer 1

由於一切都是Python中的對象，所以用作默認參數的空列表也是一個對象。更重要的是，它是同一個對象！喜歡寫作a = b = [] 你必須嘗試其他食譜，如這裏的一個。

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