python case语句_Python Switch Case三种实现方法代码实例
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云海天教程。
原文链接：https://www.cnblogs.com/xiaoqiangink/p/12978475.html