TypeError:只接受2个参数（给定1个）

Question

class DLLNode(object):

    def __init__(self, data, prev_link, next_link):  
        self.data = data
        self.prev_link = prev_link
        self.next_link = next_link


class DoublyLinkedList(object):

    def __init__(self):
        self.head=None
        self.tail=None

    def add_head(self, add_obj):
        self.head=DLLNode(add_obj,None,self.head)

---

>>> x=DoublyLinkedList
>>> x.add_head(1)
Traceback (most recent call last):
  File "<pyshell#20>", line 1, in <module>
    x.add_head(1)
TypeError: add_head() takes exactly 2 arguments (1 given)

Answer 1

猜测x不算参数，因为它没有被正确实例化。

x = DoublyLinkedList()

不是

x = DoublyLinkedList

不包括parens将DoublyLinkedList模块对象分配给x，它不会创建新对象。