創建一個類來生成ID

Question

我已經讀了一些關於自動化對象id的創建，但仍然迷路了......我試圖將以下代碼以Algorias here ......

我想要實現的是一個類，它是所有新的id請求的資源。其中的邏輯是，如果是在同一個地方，應該更容易管理...

但是當我到X設置爲訂單的一個實例，我得到如下：

>>> x = Order() 

Traceback (most recent call last): 
    File "<pyshell#20>", line 1, in <module> 
    x = Order() 
    File "C:\Python27\delete.py", line 17, in __init__ 
    self.uid = Id_Class.new_id("Order") 
TypeError: unbound method new_id() must be called with Id_Class instance as first argument (got str instance instead) 

任何幫助將不勝感激

import itertools 

class Id_Class(object):  
    new_id = itertools.count(1000).next 
    order_id = itertools.count(1000).next 
    person_id= itertools.count(1000).next 
    def new_id(self, t): # t = type of id required 
     if t == "Order": 
      self.id = Id_Class.order_id() 
     elif t == "Person": 
      self.id = Id_Class.person_id() 

class Order(object): 
    def __init__(self): 
     self.uid = Id_Class.new_id("Order") 
     self.cus='Test' 

class Person(object): 
    pass 

Answer 1

您需要在函數聲明上使用@staticmethod裝飾器。

class Id_Class(object):  
    new_id = itertools.count(1000).next 
    order_id = itertools.count(1000).next 
    person_id= itertools.count(1000).next 

    @staticmethod 
    def new_id(t): # t = type of id required 
     if t == "Order": 
      return Id_Class.order_id() 
     elif t == "Person": 
      return Id_Class.person_id() 

Answer 2

這可能是一個類的方法。類方法接收類作爲第一個參數（不像常規方法那樣是類的實例）。這樣做，您還需要返回值，以便調用者可以訪問ie。

class Id_Class(object):  
    new_id = itertools.count(1000).next 
    order_id = itertools.count(1000).next 
    person_id= itertools.count(1000).next 

    @classmethod 
    def new_id(cls, t): # t = type of id required 
     if t == "Order": 
      return cls.order_id() 
     elif t == "Person": 
      return cls.person_id() 
     else: 
      raise ValueError("Must be 'Order' or 'Person'") 

儘管你真的不需要一個類在這裏都：

new_id = itertools.count(1000).next 
order_id = itertools.count(1000).next 
person_id= itertools.count(1000).next 
def new_id(t): # t = type of id required 
    if t == "Order": 
     return order_id() 
    elif t == "Person": 
     return person_id() 

然後可以通過簡單地稱爲：

my_order_id=new_id('Order') 
my_person_id=new_id('Person') 

Answer 3

因爲你調用NEW_ID像靜態方法，請嘗試添加@staticmethod來代替：

class Id_Class(object):  
    new_id = itertools.count(1000).next 
    order_id = itertools.count(1000).next 
    person_id= itertools.count(1000).next 

    @classmethod 
    def new_id(cls, t): # t = type of id required 
     if t == "Order": 
      return Id_Class.order_id() 
     elif t == "Person": 
      return Id_Class.person_id()