Posted in Python onJune 18, 2020
Python没有switch语句,只能通过模拟来对应实现:
方法一:使用dictionary
**values = {
value1: do_some_stuff1,
value2: do_some_stuff2,
...
valueN: do_some_stuffN,
}
values.get(var, do_default_stuff)()
根据需求可以自行更改参数内容,灵活运用
def add(x,y): print x+y def minus(x,y): print x-y def multiply(x,y): print x*y def div(x,y): print x/y def fun_case_list(key,arg1,arg2): operator = { '+':add, '-':minus, '*':multiply, '/':div } if operator.has_key(key): return operator.get(key)(arg1,arg2) else: return 'No [%s] case in dic'%key #or do other func if __name__ == "__main__": fun_case_list('*',3,5) fun_case_list('l',3,4)
或者你可以自己造一个类来实现:
class switch_case(object): def case_to_function(self,case,arg1,arg2): func_name = 'case_func_'+str(case) try: method = getattr(self,func_name) return method(arg1,arg2) except AttributeError: return 'No func found in case list,do default action here' def case_func_add(self,arg1,arg2): temp = arg1 + arg2 return temp def case_func_minus(self,arg1,arg2): temp = arg1 - arg2 return temp def case_func_multiply(self,arg1,arg2): temp = arg1 * arg2 return temp def case_func_div(self,arg1,arg2): temp = arg1 / arg2 return temp func = 'minus' case = switch_case() print case.case_to_function(func,2,5) #或者是构造属性去送参数,看个人喜好 class switch_case(object): def __init__(self, case, arg1, arg2): self.case = str(case) self.arg1 = arg1 self.arg2 = arg2 def case_to_function(self): func_name = 'case_func_'+str(self.case) try: method = getattr(self,func_name) return method() except AttributeError: return 'No func found in case list,do default action here' def case_func_add(self): temp = self.arg1 + self.arg2 return temp def case_func_minus(self): temp = self.arg1 - self.arg2 return temp def case_func_multiply(self): temp = self.arg1 * self.arg2 return temp def case_func_div(self): temp = self.arg1 / self.arg2 return temp func = 'minxus' case = switch_case(func,2,5) print case.case_to_function()
方法二:使用lambda
result = {
'a': lambda x: x * 5,
'b': lambda x: x + 7,
'c': lambda x: x - 2
}[value](x)
方法三:Brian Beck提供了一个类 switch 来实现switch的功能
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 v = 'two' 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
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持三水点靠木。
Python Switch Case三种实现方法代码实例
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