python - python对象中的隐式项目分配

Question

我希望能够在不指定的情况下为类的属性赋值。

我想做什么

A)

class HoldingStuff(object):

    def __init__(self, **args):
        self.a = 1
        self.b = '1'
        self.c = 2
        self.d = '3'
        self.e = 4
        for arg in args:
            self[arg] = args[arg]

first = HoldingStuff(a=5)
second = HoldingStuff(d=2, e='2')

当然，我可以在保存值的类中使用字典。然而，这有一个很大的缺点，因为那时我不能对属性使用代码完成。这使得它们难以重用和查找。 (属性是用于模拟的大量可变参数列表。)

什么有效(并且不切实际)

B)

class HoldingStuff(object):

    def __init__(self, **args):
        self['a'] = 1
        self['b'] = '1'
        self['c'] = 2
        self['d'] = '3'
        self['e'] = 4
        for arg in args:
            self[arg] = args[arg]

什么有效

C)

class HoldingStuff(MutableMapping):

    def __init__(self, **args):
        self.a = 1
        self.b = '1'
        self.c = 2
        self.d = '3'
        self.e = 4
        for arg in args:
            self[arg] = args[arg]

    def __setitem__(self, k, v) -> None:
        if k =='a':
            self.a = v
        elif k =='b':
            self.b = v
        elif k =='c':
            self.c = v
        elif k =='d':
            self.d = v
        elif k =='e':
            self.e = v
        else:
            print(k, "Not available for class.")

    def __delitem__(self, v) -> None:
        pass

    def __getitem__(self, k) -> _VT_co:
        if k =='a':
            return self.a
        elif k =='b':
            return self.b
        elif k =='c':
            return self.c
        elif k =='d':
            return self.d
        elif k =='e':
            return self.e
        else:
            print(k, "Not available for class.")

    def __len__(self) -> int:
        return 5

    def __iter__(self):
        print("Not implemented")

函数 __setitem__ 和 __getitem__ 看起来很明显而且重复!

问题有没有办法减少示例 C) 的源代码，使其以示例 A) 的隐式方式工作？

Answer 1

使用setattr .

for name, value in args.items():
    setattr(self, name, value)