stack.py

python的典型方法,对初学的python的人有一定的借鉴作用。

class stack(object):
    class node(object):
        def __init__(self,item):
            self.item = item
            self.next = None

    class emptystackException(Exception):
        pass

    def __init__(self):
        self.top = None

    def push(self, obj):
        x = stack.node(obj)
        x.next = self.top
        self.top = x

    def pop(self):
        if self.top:
            x = self.top
            self.top = x.next
            return x.item
        else:
            raise stack.emptystackException
    def empty(self):
        return not bool(self.top)

S = stack()
for i in range(10):
    S.push(i)
print S.empty()
while not S.empty():
    print S.pop()
S.pop()