折腾：
期间，想要去给一个enum的值判断，实现一定的逻辑
需要用到 switch case
搜：
python switch case
Python中为什么没有switch语法结构，有什么代替方案吗？ – 知乎
def case1(somearg): pass def case2(somearg): pass def case3(somearg): pass switch={ 1: case1, 2: case2, 3: case3 } switch[case](arg) |
Design and History FAQ — Python 2.7.12 documentation
Replacements for switch statement in Python? – Stack Overflow
“
def f(x):
return {
‘a’: 1,
‘b’: 2,
}.get(x, 9) # 9 is default if x not found
”
“
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dictionary
values = {
value1: do_some_stuff1,
value2: do_some_stuff2,
…
valueN: do_some_stuffN,
}
values.get(var, do_default_stuff)()
具体请参考: Python switch statement
这个方法的缺点是:我不知道do_some_stuff是不是允许多个语句，如何实现，
也许是可以的，我不知道-.-
B.使用lambda
在PHP中，
switch ($value) {
case ‘a’:
$result = $x * 5;
break;
case ‘b’:
$result = $x + 7;
break;
case ‘c’:
$result = $x – 2;
break;
}
在python中:
result = {
‘a’: lambda x: x * 5,
‘b’: lambda x: x + 7,
‘c’: lambda x: x – 2
}[value](x)
具体参考: Switch statements in Python
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
”
为什么Python中没有Switch/Case语句? – Python – 伯乐在线
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