python - 基于python中类对象的属性(不是属性)的最小值/最大值

Question

考虑以下代码片段。

class MyClass(object):
  @property
  def foo(self):
    return self._foo      

l = [my_class1, my_class2]

min(l, key=MyClass.foo) # doesn't work because foo is not callable. 
                        # "TypeError: 'property' object is not callable"

有没有办法让它发挥作用？

Answer 1

使用 operator.attrgetter :

min(l, key=operator.attrgetter('foo'))

---

例子:

>>> class MyClass(object):
...     def __init__(self, val):
...         self._foo = val
...     def __repr__(self):
...         return 'MyClass({})'.format(self._foo)
...     @property
...     def foo(self):
...         return self._foo
... 
>>> import operator
>>> min([MyClass(3), MyClass(1), MyClass(2)], key=operator.attrgetter('foo'))
MyClass(1)