python用字典实现switch

因为python没有switch语句,一直以来都是用多个if..elif..来实现相同逻辑.

今天看到一个凶残暴力的实现方式,于是动手写写,记下来

from distutils import log

def stateA():
	log.warn('stateA called')

def stateB():
	log.warn('stateB called')

def stateC():
	log.warn('stateC called')

def stateDefault():
	log.warn('stateDefault called')

cases = {'a':stateA, 'b':stateB, 'c':stateC}

def switch(case):
	if case in cases:
		cases[case]()
	else:
		stateDefault()

def test():
	switch('b')
	switch('c')
	switch('a')
	switch('x')

test()

如果每个分支需要处理的逻辑很少,更是可以用lamdba简化,如下:

from distutils import log


cases = {'a':lambda:log.warn('in stateA'), 'b':lambda:log.warn('in stateB'),
		'c':lambda:log.warn('in stateC')}

def switch(case):
	if case in cases:
		cases[case]()
	else:
		log.warn('in stateDefualt')

def test():
	switch('b')
	switch('c')
	switch('a')
	switch('x')

test()