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方式一
Python 3.10版本 更新了类似其他语言的switch case结构,所以最好的方法是直接更新到python3.10,直接使用match case 语句:
C语言:
switch (expression) {
case constant-expression :
statement(s);
break; /* 可选的 */
case constant-expression :
statement(s);
break; /* 可选的 */
/* 您可以有任意数量的 case 语句 */
default : /* 可选的 */
statement(s);
}
Python:
flag = False
match (100, 200):
case (100, 300): # Mismatch: 200 != 300
print('Case 1')
case (100, 200) if flag: # Successful match, but guard fails
print('Case 2')
case (100, y): # Matches and binds y to 200
print(f'Case 3, y: {
y}')
case _: # Pattern not attempted
print('Case 4, I match anything!')
#PEP 634: Structural Pattern Matching
match subject:
case <pattern_1>:
<action_1>
case <pattern_2>:
<action_2>
case <pattern_3>:
<action_3>
case _:
<action_wildcard>
更详细的介绍:
https://blog.csdn.net/Datapad/article/details/123205558
方式二
使用函数实现类似switch case的效果:
def switch_case(value):
switcher = {
0: "zero",
1: "one",
2: "two",
}
return switcher.get(value, 'wrong value')
使用匿名函数方式实现:
def foo(var,x):
return {
'a': lambda x: x+1,
'b': lambda x: x+2,
'c': lambda x: x+3,
}[var](x)
方式三
自定义switch case类:
# 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
# break is used here to look as much like the real thing as possible, but
# elif is generally just as good and more concise.
# Empty suites are considered syntax errors, so intentional fall-throughs
# should contain 'pass'
c = 'z'
for case in switch(c):
if case('a'): pass # only necessary if the rest of the suite is empty
if case('b'): pass
# ...
if case('y'): pass
if case('z'):
print "c is lowercase!"
break
if case('A'): pass
# ...
if case('Z'):
print "c is uppercase!"
break
if case(): # default
print "I dunno what c was!"
# As suggested by Pierre Quentel, you can even expand upon the
# functionality of the classic 'case' statement by matching multiple
# cases in a single shot. This greatly benefits operations such as the
# uppercase/lowercase example above:
import string
c = 'A'
for case in switch(c):
if case(*string.lowercase): # note the * for unpacking as arguments
print "c is lowercase!"
break
if case(*string.uppercase):
print "c is uppercase!"
break
if case('!', '?', '.'): # normal argument passing style also applies
print "c is a sentence terminator!"
break
if case(): # default
print "I dunno what c was!"
# Since Pierre's suggestion is backward-compatible with the original recipe,
# I have made the necessary modification to allow for the above usage.
参考:https://www.cnblogs.com/gerrydeng/p/7191927.html
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