Python 函数名作为字典值

　　Python中是没有switch的, 所以有时我们需要用switch的用法, 就只能通过if else来实现了. 但if else写起来比较冗长,

这时就可以使用Python中的dict来实现, 比switch还要简洁. 用法如下:

　　如果是key1的情况就执行func1, 如果是key2的情况就执行func2...(func1, func2...所有的函数的参数形式需要相同),

假设各个函数参数均为(arg1, arg2):

dictName = {"key1":func1, "key2":func2, "key3":func3"...}　　#字典的值直接是函数的名字,不能加引号

dictName[key](arg1, arg2)

　　示例代码如下:

#!/usr/bin/python

#File: switchDict.py

#Author: lxw

#Time: 2014/10/05

import re

def add(x, y):

    return x + y

def sub(x, y):

    return x - y

def mul(x, y):

    return x * y

def div(x, y):

    return x / y

def main():

    inStr = raw_input("Please input the easy expression:(e.g. 1 + 2.But 1 + 2 + 3 are not accepted.\n")

    inList = re.split("(\W+)", inStr)

    inList[1] = inList[1].strip()

    print("-------------------------")

    print(inList)

    print("-------------------------")

    #Method 1:

    if inList[1] == "+":

        print(add(int(inList[0]), int(inList[2])))

    elif inList[1] == "-":

        print(sub(int(inList[0]), int(inList[2])))

    elif inList[1] == "*":

        print(mul(int(inList[0]), int(inList[2])))

    elif inList[1] == "/":

        print(div(int(inList[0]), int(inList[2])))

    else:

        pass

    #Method 2:

    try:

        operator = {"+":add, "-":sub, "*":mul, "/":div}

        print(operator[inList[1]](int(inList[0]), int(inList[2])))

    except KeyError:

        pass

if __name__ == '__main__':

    main()

Output:

PS J:\> python .\switchDict.py

Please input the easy expression:(e.g. 1 + 2.But 1 + 2 + 3 are not accepted.

1 + 2

-------------------------

['', '+', '']

-------------------------

3

3

PS J:\> python .\switchDict.py

Please input the easy expression:(e.g. 1 + 2.But 1 + 2 + 3 are not accepted.

4 - 9

-------------------------

['', '-', '']

-------------------------

-5

-5

PS J:\> python .\switchDict.py

Please input the easy expression:(e.g. 1 + 2.But 1 + 2 + 3 are not accepted.

6 / 5

-------------------------

['', '/', '']

-------------------------

1

1

PS J:\> python .\switchDict.py

Please input the easy expression:(e.g. 1 + 2.But 1 + 2 + 3 are not accepted.

1 9 9

-------------------------

['', '', '', ' ', '']

-------------------------

PS J:\> python .\switchDict.py

Please input the easy expression:(e.g. 1 + 2.But 1 + 2 + 3 are not accepted.

1 ( 9

-------------------------

['', '(', '']

-------------------------

PS J:\>

　　个人感觉, 如果想用switch来解决某个问题, 并且每种情况下的操作在形式上是相同的(如都执行某个函数并且这些函数有

相同的参数), 就可以用这种方法来实现.

巴特西

Python 函数名作为字典值

最新文章

热门文章