Stack的简单实现。

stack.py

#! /usr/bin/env python
# -*- coding: utf-8 -*-
# This is a Stack implementing in list.


class Stack():
    def __init__(self):
        self._content = list()

    def __len__(self):
        return len(self._content)

    def _is_empty(self):
        return len(self) == 0

    def __str__(self):
        return str(self._content)

    def push(self, element):
        self._content.append(element)

    def pop(self):
        assert not self._is_empty()
        self._content.pop()

    def peek(self):
        assert not self._is_empty()
        return self._content[-1]


# The following shows how to use class Stack
if __name__ == "__main__":
    test_stack = Stack()
    for i in range(5):
        test_stack.push(i ** 2)

    print test_stack._is_empty
    print "Operation peek: ", test_stack.peek()
    test_stack.pop()
    print "After Operation pop: ", test_stack

'''
    for i in range(5):
        test_stack.pop()
        print test_stack
'''