《Python核心编程（第2版）》读书笔记（6）之用列表模拟堆栈（关键词：Python/列表/堆栈/stack.py）



stack = []

def pushit():
    stack.append(raw_input('enter new string: ').strip())

def popit():
    if len(stack)==0:
        print 'can not pop from an empty stack!'
    else:
        # 用反单引号（`）来代替repr()函数，把字符串的内容用引号括起来显示，而不是单单显示字符串的内容。
        print 'removed [', `stack.pop()`, ']'

def viewstack():
    print stack    # calls str() internally

CMDs = {'u': pushit, 'o': popit, 'v': viewstack}

def showmenu():
    pr = """
    p(U)sh
    p(o)p
    (V)iew
    (Q)uit
    enter choice: """

    while True:
        while True:
            try:
                choice = raw_input(pr).strip()[0].lower()
            except (EOFError,KeyboardInterrupt,IndexError):
                choice = 'q'


            print '\nyou picked: [%s]' % choice
            if choice not in 'uovq':
                print 'invalid option, try again'
            else:
                break

        if choice == 'q':
            break
        CMDs[choice]()

if __name__ == '__main__':
    showmenu()