Python 函数名作为字典值，,　　Python中是

Python 函数名作为字典值，,　　Python中是

　　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: 2014/10/05import redef add(x, y):    return x + ydef sub(x, y):    return x - ydef mul(x, y):    return x * ydef div(x, y):    return x / ydef 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:        passif __name__ == ‘__main__‘:    main()

Output:

PS J:\> python .\switchDict.pyPlease input the easy expression:(e.g. 1 + 2.But 1 + 2 + 3 are not accepted.1 + 2-------------------------[‘1‘, ‘+‘, ‘2‘]-------------------------33PS J:\> python .\switchDict.pyPlease input the easy expression:(e.g. 1 + 2.But 1 + 2 + 3 are not accepted.4 - 9-------------------------[‘4‘, ‘-‘, ‘9‘]--------------------------5-5PS J:\> python .\switchDict.pyPlease input the easy expression:(e.g. 1 + 2.But 1 + 2 + 3 are not accepted.6 / 5-------------------------[‘6‘, ‘/‘, ‘5‘]-------------------------11PS J:\> python .\switchDict.pyPlease input the easy expression:(e.g. 1 + 2.But 1 + 2 + 3 are not accepted.1 9 9-------------------------[‘1‘, ‘‘, ‘9‘, ‘ ‘, ‘9‘]-------------------------PS J:\> python .\switchDict.pyPlease input the easy expression:(e.g. 1 + 2.But 1 + 2 + 3 are not accepted.1 ( 9-------------------------[‘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.

Python 函数名作为字典值