【Python 笔记】Python中 swich...case 的实现

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其他语言中,switch语句大概是这样的
switch (var){    case value1: do_some_stuff1();    case value2: do_some_stuff2();    ...    case valueN: do_some_stuffN();    default: do_default_stuff();}

而python本身没有switch语句,解决方法有以下3种:A.使用dictionaryvalues = {           value1: do_some_stuff1,           value2: do_some_stuff2,           ...           valueN: do_some_stuffN,         }values.get(var, do_default_stuff)()B.使用lambdaresult = {  'a': lambda x: x * 5,  'b': lambda x: x + 7,  'c': lambda x: x - 2}[value](x)C.Brian Beck提供了一个类 switch 来实现其他语言中switch的功能
# This class provides the functionality we want. You only need to look at# this if you want to know how this works. It only needs to be defined# once, no need to muck around with its internals.class switch(object):    def __init__(self, value):        self.value = value        self.fall = False    def __iter__(self):        """Return the match method once, then stop"""        yield self.match        raise StopIteration    def match(self, *args):        """Indicate whether or not to enter a case suite"""        if self.fall or not args:            return True        elif self.value in args: # changed for v1.5, see below            self.fall = True            return True        else:            return False# The following example is pretty much the exact use-case of a dictionary,# but is included for its simplicity. Note that you can include statements# in each suite.v = 'ten'for case in switch(v):    if case('one'):        print 1        break    if case('two'):        print 2        break    if case('ten'):        print 10        break    if case('eleven'):        print 11        break    if case(): # default, could also just omit condition or 'if True'        print "something else!"        # No need to break here, it'll stop anyway
转自:http://blog.csdn.net/suiyunonghen/article/details/3734135

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