相关疑难解决方法(0)

我写一个元类读取类的属性,并将它们存储在列表中,但我想要的清单(cls.columns)尊重声明的顺序(即:mycol2,mycol3,zut,cool,menfin,a在我的例子):

import inspect
import pprint

class Column(object):
    pass

class ListingMeta(type):
    def __new__(meta, classname, bases, classDict):
        cls = type.__new__(meta, classname, bases, classDict)
        cls.columns = inspect.getmembers(cls, lambda o: isinstance(o, Column)) 
        cls.nb_columns = len(cls.columns)
        return cls

class Listing(object):
    __metaclass__ = ListingMeta
    mycol2 = Column()
    mycol3 = Column()
    zut = Column()
    cool = Column()
    menfin = Column()
    a = Column()

pprint.pprint(Listing.columns)

结果:

[('a', <__main__.Column object at 0xb7449d2c>),
 ('cool', <__main__.Column object at 0xb7449aac>), …