python中的switch

1.

class MyCommandDispatcher(object):
    def do_a(self):
      # do stuff

    def do_b(self):
      # do stuff

    def do_5(self):
      # do stuff

    def default(self):
      # do stuff

    def switch(self, option):
        getattr(self, 'do_' + str(option), self.default)()

d = MyCommandDispatcher()
d.switch('a')
d.switch(5) 

2.

result = {
  'a': lambda x: x * 5,
  'b': lambda x: x + 7,
  'c': lambda x: x - 2
}[value](x)

3.if
elif
else