python - 您如何解压方法参数来为它们分配类属性？

Question

我经常做这种事情:

class Box:
    def __init__(self):
        some_setup_stuff()
    def configure(
        self,
        color               = "#ffffff",
        weight              = 1,
        empathy             = 97,
        angle_x             = 0,
        angle_y             = 0,
        angle_z             = 0,
        displacement_x      = 0,
        displacement_y      = 0,
        displacement_z      = 0
        ):
        self.color          = color
        self.weight         = weight
        self.empathy        = empathy
        self.angle_x        = angle_x
        self.angle_y        = angle_y
        self.angle_z        = angle_z
        self.displacement_x = displacement_x
        self.displacement_y = displacement_y
        self.displacement_z = displacement_z
    def open(self):
        reveal_head()

是否有一些简洁、小巧、相当明智的方法来将传递给类方法的参数“解包”到类的属性中(同时保持显式指定的默认值)？比如，我在想也许 locals() 可以以某种方式围绕方法的第一行使用，但这对我来说并不明显。

所以我们最终可能会得到类似这样的结果:

class Box:
    def __init__(self):
        some_setup_stuff()
    def configure(
        self,
        color               = "#ffffff",
        weight              = 1,
        empathy             = 97,
        angle_x             = 0,
        angle_y             = 0,
        angle_z             = 0,
        displacement_x      = 0,
        displacement_y      = 0,
        displacement_z      = 0
        ):
        # magic possibly involving locals()
    def open(self):
        reveal_head()

它可以这样使用:

>>> box = Box()
>>> box.configure(empathy = 98)
>>> box.weight
1
>>> box.empathy
98

Answer 1

这是一个有点老套的方法。构建一个包含允许参数默认值的 defaults 字典。然后在对键进行一些错误检查后，用 **kwargs 更新 self.__dict__:

class Box:
    def __init(self):
        pass
    def configure(self, **kwargs):
        defaults = {
            "color": "#ffffff",
            "weight": 1,
            "empathy": 97,
            "angle_x": 0,
            "angle_y": 0,
            "angle_z": 0,
            "displacement_x": 0,
            "displacement_y": 0,
            "displacement_z": 0
        }
        bad_args = [k for k in kwargs if k not in defaults]
        if bad_args:
            raise TypeError("configure() got unexpected keyword arguments %s"%bad_args)
        self.__dict__.update(defaults)
        self.__dict__.update(kwargs)

现在您可以:

box = Box()
box.configure(empathy = 98)
print(box.weight)
#1
print(box.empathy)
#98

但如果你这样做了:

box.configure(wieght = 2)
#TypeError: configure() got unexpected keyword arguments ['wieght']