【发布时间】：2017-07-22 18:34:59
【问题描述】：
我想知道是否可以防止用户在使用子类时调用父类的方法。同时，我希望这些方法对子类本身的方法可用。
例如，假设我有一个链表的实现。然后我通过继承（不确定它是否是好的设计......）基于它实现堆栈 ADT。因此，我希望对 Stack 类的用户“隐藏” LinkedList 类的方法。
链表：
class LinkedList(object):
class Node(object):
"""
Inner class of LinkedList. Contains a blueprint for a node of the LinkedList
"""
def __init__(self, v, n=None):
"""
Initializes a List node with payload v and link n
"""
self.value=v
self.next=n
def __init__(self):
"""
Initializes a LinkedList and sets list head to None
"""
self.head=None
def insert(self, v):
"""
Adds an item with payload v to beginning of the list
in O(1) time
"""
Node = self.Node(v, self.head)
self.head = Node
print("Added item: ", Node.value, "self.head: ", self.head.value)
def size(self):
"""
Returns the current size of the list. O(n), linear time
"""
current = self.head
count = 0
while current:
count += 1
current = current.next
return count
def search(self, v):
"""
Searches the list for a node with payload v. Returns the node object or None if not found. Time complexity is O(n) in worst case.
"""
current = self.head
found = False
while current and not found:
if current.value == v:
found = True
else:
current = current.next
if not current:
return None
return current
def delete(self, v):
"""
Searches the list for a node with payload v. Returns the node object or None if not found. Time complexity is O(n) in worst case.
"""
current = self.head
previous = None
found = False
while current and not found:
if current.value == v:
found = True
else:
previous = current
current = current.next
# nothing found, return None
if not current:
return None
# the case where first item is being deleted
if not previous:
self.head = current.next
# item from inside of the list is being deleted
else:
previous.next = current.next
return current
def __str__(self):
"""
Prints the current list in the form of a Python list
"""
current = self.head
toPrint = []
while current != None:
toPrint.append(current.value)
current = current.next
return str(toPrint)
堆栈：
from PythonADT.lists import LinkedList
class Stack(LinkedList):
def __init__(self):
LinkedList.__init__(self)
【问题讨论】：
-
不，这可能不是一个好的设计。如果不想暴露相同的接口，compose 不要inherit。
-
如果 Stack 不能履行 LinkedList 的接口承诺，它不应该扩展 LinkedList。
-
如官方 Python 文档 "9.6. Private Variables" 中所述，可以在
class中保护方法。只需通过以两个下划线开头的命名来声明该函数（例如：__private_search(self):）。 -
@jonrsharpe 你是在建议这样的事情吗？
class Stack(object): def __init__(self): self.items = LinkedList()之后我将继续实现 Stack ADT，但在幕后使用 LinkedList。 -
是的，就是这样。或
self._items表示列表本身也不属于堆栈的公共接口。
标签： python python-2.7 python-3.x oop inheritance