python 实现namedtuple（元类）

def namedtuple(tuple_name, attrs):
class Meta(type):
def __call__(self, *args):
return type.__call__(self, args)
attrs_set = set(attrs)
def __init__(self, args):
for key, value in zip(attrs, args):
self.__dict__[key]=value
def __str__(self):
values = [str(x) for x in self.__dict__.values()]
return tuple_name+'(' + ', '.join(values) + ')'
def to_dict(self):
return self.__dict__
return Meta(tuple_name, (tuple,),{'attr_keys':attrs_set,'__init__':__init__,'__str__':__str__,'to_dict':to_dict})

def __call__(self, *args):
return type.__call__(self, args)

__init__

def __init__(self, args):
for key, value in zip(attrs, args):
self.__dict__[key]=value

__init__

self.__dict__

In [1]: from namedtuple_like import namedtuple

In [2]: Point = namedtuple('p',['x','y'])

In [3]: p = Point(1,2)

In [4]: p.x
Out[4]: 1

In [5]: p.y
Out[5]: 2

In [8]: p.to_dict()
Out[8]: {'x': 1, 'y': 2}

In [12]: print(p)
p(1, 2)