使用属性装饰器在函数内部使用列表理解从命名元组中恢复值？

Question

我正在关注 python documentation and also this，但在使用 getattr 时我得到了一个属性对象指针，我无法获取或打印我正在寻找的值。

class DefaultSettings():
    """This contains default game settings."""
    def __init__(self):
        """Default settings"""
        self.Keyboard = namedtuple('Keyboard', ['gas', 'reverse', 'sbreak', 'ebreak', 'left', 'right'])
        self.Keyboard(gas = 'WKEY', reverse = 'SKEY', sbreak = 'SKEY', ebreak = 'SPACEKEY', left = 'AKEY', right = 'DKEY')
    @property
    def keyboard(self):
        return [getattr(self.Keyboard, key) for key in self.Keyboard._fields]

settings = DefaultSettings()
print("keyboard 1: ",settings.keyboard)
print("Keyboard 2: ",settings.Keyboard)
print("keyboard 3: ",settings.Keyboard._fields)
print("Keyboard 4: ", DefaultSettings.keyboard.__get__)
print("Keyboard 5: ", DefaultSettings.keyboard.__get__(settings, DefaultSettings))
for key in settings.Keyboard._fields:
    print(getattr(settings.Keyboard, key))

和输出：

D:\Games\BSR\scripts>python config.py
keyboard 1:  [<property object at 0x000001C18DDC4778>, <property object at 0x000001C18DDC4AE8>, <property object at 0x000001C18DDC4B38>, <property object at 0x000001C18DDC4B88>, <property object at 0x000001C18DDC4BD8>, <property object at 0x000001C18DDC4C28>]
Keyboard 2:  <class '__main__.Keyboard'>
keyboard 3:  ('gas', 'reverse', 'sbreak', 'ebreak', 'left', 'right')
Keyboard 4:  <method-wrapper '__get__' of property object at 0x000001C18DDC4598>
Keyboard 5:  [<property object at 0x000001C18DDC4778>, <property object at 0x000001C18DDC4AE8>, <property object at 0x000001C18DDC4B38>, <property object at 0x000001C18DDC4B88>, <property object at 0x000001C18DDC4BD8>, <property object at 0x000001C18DDC4C28>]
<property object at 0x000001C18DDC4778>
<property object at 0x000001C18DDC4AE8>
<property object at 0x000001C18DDC4B38>
<property object at 0x000001C18DDC4B88>
<property object at 0x000001C18DDC4BD8>
<property object at 0x000001C18DDC4C28>
D:\Games\BSR\scripts>

Answer 1

问题出在您的 __init__ 方法中：

def __init__(self):
    """Default settings"""
    self.Keyboard = namedtuple('Keyboard', ['gas', 'reverse', 'sbreak', 'ebreak', 'left', 'right'])
    self.Keyboard(gas = 'WKEY', reverse = 'SKEY', sbreak = 'SKEY', ebreak = 'SPACEKEY', left = 'AKEY', right = 'DKEY')

正如the doc of namedtuple所说：

Returns a new tuple subclass named typename

因此，在 __init__ 方法的第一行中，您初始化了一个新的 class 并将其分配给字段 self.Keyboard，并在下一行中创建了一个新的 [=17] =] 的 class self.Keyboard 但是将它分配给任何地方，self.Keyboard 仍然是一个 class 对象。所以下面的代码所做的是 iterating/printing 个 class 的属性和方法，而不是一个实例。我猜你想要的可能是：

def __init__(self):
    Keyboard = namedtuple('Keyboard', ['gas', 'reverse', 'sbreak', 'ebreak', 'left', 'right'])
    self.Keyboard = Keyboard(gas = 'WKEY', reverse = 'SKEY', sbreak = 'SKEY', ebreak = 'SPACEKEY', left = 'AKEY', right = 'DKEY')

然后你会得到你想要的值。

使用属性装饰器在函数内部使用列表理解从命名元组中恢复值？

Values recovery from named tuples using list comprehension inside function with property decorator?

python

namedtuple

getattr

python-2.7

使用 属性 装饰器在函数内部使用列表理解从命名元组中恢复值？

Values recovery from named tuples using list comprehension inside function with property decorator?

python

namedtuple

getattr

python-2.7

使用属性装饰器在函数内部使用列表理解从命名元组中恢复值？