我可以覆盖一个namedtuple的字符串形式吗？

Question

例如:

>>> Spoken = namedtuple("Spoken", ["loudness", "pitch"])
>>> s = Spoken(loudness=90, pitch='high')
>>> str(s)
"Spoken(loudness=90, pitch='high')"

我想要的是:

>>> str(s)
90

那就是我希望字符串表示显示响度属性.这可能吗 ？

Answer 1

是的,这并不难做,并且在namedtuple文档中有一个例子.

该技术是创建一个添加自己的str方法的子类:

>>> from collections import namedtuple
>>> class Spoken(namedtuple("Spoken", ["loudness", "pitch"])):
        __slots__ = ()
        def __str__(self):
            return str(self.loudness)

>>> s = Spoken(loudness=90, pitch='high')
>>> str(s)
'90'

Answer 2

您可以为它定义一个函数:

def print_loudness(self):
    return str(self.loudness)

并将其分配给__str__:

Spoken.__str__ = print_loudness