Python那些优雅的写法：switch-case

Python那些优雅的写法：switch-case

引言

实际上Python是没有所谓的switch case写法的，熟悉C艹和Java的同学可能已经习惯了用switch case结构去优雅的处理一些事情，比如这样：

switch(变量){
case 变量值1:
    //...;
    break;
case 变量值2:
    //...;
    break;
  ...
case default:
    //...;
    break;
}

但是在Python中，官方对switch case的需求是这样回复的：
" You can do this easily enough with a sequence of if... elif... elif... else. There have been some proposals for switch statement syntax, but there is no consensus (yet) on whether and how to do range tests. "
感觉有点low。

解决

可用字典方法解决这个问题：

# switch = {"valueA":functionA,"valueB":functionB,"valueC":functionC}
# try:
#　　switch["value"]() #执行相应的方法。
# except KeyError as e:
#       pass 或 functionX #执行default部分

switch = {
    "a":lambda x:x*2,
    "b":lambda x:x*3,
    "c":lambda x:x**x
}
try:
    swtich["c"](6)
except KeyError as e:
    pass