创建列表/节点类 Python

Create list/node class Python

提问by SagittariusA

As exercise, I would like to create my own node/list class. Anyway I don't understand how to add a node to list...here's my code:

作为练习，我想创建自己的节点/列表类。无论如何，我不明白如何将节点添加到列表中……这是我的代码：

class Node:
    def __init__(self, value):
        self.element = value
        self.nextEl = None

    def getEl(self):
        return self.element

    def getNext():
        return self.nextEl

class List:
    def __init__(self, fnode):
        self.firstNode = fnode

    def add(self, newNode):

    def printList(self):
        temp = self.firstNode
        while (temp != None):
            print temp.element
            temp = temp.nextEl

回答by Martijn Pieters

You need to find the last node without a .nextElpointer and add the node there:

您需要找到没有.nextEl指针的最后一个节点并在那里添加节点：

def add(self, newNode):
    node = self.firstNode
    while node.nextEl is not None:
        node = next.nextEl
    node.nextEl = newNode

Because this has to traverse the whole list, most linked-list implementations also keep a reference to the last element:

因为这必须遍历整个列表，大多数链表实现还保留对最后一个元素的引用：

class List(object):
    first = last = None

    def __init__(self, fnode):
        self.add(fnode)

    def add(self, newNode):
        if self.first is None:
            self.first = self.last = newNode
        else:
            self.last.nextEl = self.last = newNode

Because Python assigns to multiple targets from left to right, self.last.nextElis set to newNodebefore self.last.

因为 Python 从左到右分配给多个目标，self.last.nextEl所以设置为newNodebefore self.last。

Some style notes on your code:

关于您的代码的一些样式说明：

• Use is Noneand is not Noneto test if an identifier points to None(it's a singleton).
• There is no need for accessors in Python; just refer to the attributes directly.

• Unless this is Python 3, use new-style classes by inheriting from object:

  class Node(object):
      # ...
  

• 使用is None和is not None测试标识符是否指向None（它是一个单例）。
• Python 中不需要访问器；直接引用属性就行了。

• 除非这是 Python 3，否则通过继承使用新式类object：

  class Node(object):
      # ...