Python __repr__用于所有成员变量 [英] Python __repr__ for all member variables

问题描述

为具有成员变量x和y的类Foo实现__repr__，是否有一种自动填充字符串的方法?无效的示例:

Implementing __repr__ for a class Foo with member variables x and y, is there a way to automatically populate the string? Example that does not work:

class Foo(object):
    def __init__(self, x, y):
        self.x = x
        self.y = y
    def __repr__(self):
        return "Foo({})".format(**self.__dict__)

>>> foo = Foo(42, 66)
>>> print(foo)
IndexError: tuple index out of range

另一个:

from pprint import pprint
class Foo(object):
    def __init__(self, x, y):
        self.x = x
        self.y = y
    def __repr__(self):
        return "Foo({})".format(pprint(self.__dict__))

>>> foo = Foo(42, 66)
>>> print(foo)
{'x': 42, 'y': 66}
Foo(None)

是的，我可以将方法定义为

Yes I could define the method as

    def __repr__(self):
        return "Foo({x={}, y={}})".format(self.x, self.x)

但是当成员变量很多时，这变得很乏味.

but this gets tedious when there are many member variables.

推荐答案

当我想要这样的东西时，我将其用作混合:

I use this as a mixin when I want something like that:

class SimpleRepr(object):
    """A mixin implementing a simple __repr__."""
    def __repr__(self):
        return "<{klass} @{id:x} {attrs}>".format(
            klass=self.__class__.__name__,
            id=id(self) & 0xFFFFFF,
            attrs=" ".join("{}={!r}".format(k, v) for k, v in self.__dict__.items()),
            )

它提供了类名，(缩短的)id和所有属性.

It gives the class name, the (shortened) id, and all of the attributes.

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