Python中的通用__eq __()方法

Question

我想__eq__()为以下类创建一个通用方法.基本上我希望能够添加另一个属性(nick)而不必更改__eq__()

我想我可以通过迭代来以某种方式做到这一点,dir()但我想知道是否有办法创建一个只提供属性的理解.

 class Person:
     def __init__(self, first, last):
         self.first=first
         self.last=last

     @property
     def first(self):
         assert(self._first != None)
         return self._first
     @first.setter
     def first(self,fn):
         assert(isinstance(fn,str))
         self._first=fn

     @property
     def last(self):
         assert(self._last != None)
         return self._last
     @last.setter
     def last(self,ln):
         assert(isinstance(ln,str))
         self._last=ln
     @property
     def full(self):
         return f'{self.first} {self.last}'

     def __eq__(self, other):
         return self.first==other.first and self.last==other.last

 p = Person('Raymond', 'Salemi')
 p2= Person('Ray', 'Salemi')

Answer 1

您可以使用__dict__检查是否所有属性都相同,所有属性都可以缩放:

如果对象不匹配类型,我只需返回False.

class Person:
    def __init__(self, first, last, nick):
        self.first = first
        self.last = last
        self.nick = nick

    def __eq__(self, other):
        return self.__dict__ == other.__dict__  if type(self) == type(other) else False

>>> p = Person('Ray', 'Salemi', 'Ray')
>>> p2= Person('Ray', 'Salemi', 'Ray')
>>> p3 = Person('Jared', 'Salemi', 'Jarbear')

>>> p == p2
True
>>> p3 == p2
False
>>> p == 1
False

Answer 2

Class您可以使用如下结构获取 a 的所有属性：

from itertools import chain
@classmethod
def _properties(cls):
    type_dict = dict(chain.from_iterable(typ.__dict__.items() for typ in reversed(cls.mro())))
    return {k for k, v in type_dict.items() if 'property' in str(v)}

会__eq__变成这样：

def __eq__(self, other):
    properties = self._properties() & other._properties()
    if other._properties() > properties and self._properties() > properties:
        # types are not comparable
        return False
    try:
        return all(getattr(self, prop) == getattr(other, prop) for prop in properties)
    except AttributeError:
        return False

使用的原因reversed(cls.mro())是这样的也有效：

class Worker(Person):
    @property
    def wage(self):
        return 0

p4 = Worker('Raymond', 'Salemi')

print(p4 == p3)

True