python 元类

class_dict = {}
exec("""
country = "China"
def __init__(self,name,age,sex):
    self.name = name
    self.age = age
    self.sex =sex

def say_hello(self):
    print('%s 说：你好！' %self.name)
""", globals(), class_dict)
my_class = type('my_class', (object,), class_dict)
m = my_class('小明', 12, '男')
m.say_hello()