如何從聲明的描述符生成類的 __init__ 方法？

Question

python文檔中的示例：

class Component:

    name = String(minsize=3, maxsize=10, predicate=str.isupper)
    kind = OneOf('wood', 'metal', 'plastic')
    quantity = Number(minvalue=0)

    def __init__(self, name, kind, quantity):
        self.name = name
        self.kind = kind
        self.quantity = quantity

如何讓 python 為我生成__init__方法？

Answer 1

您可以使用 python 的數據類，它會工作得很好：

from dataclasses import dataclass

@dataclass
class Component:

    name: str = String(minsize=3, maxsize=10, predicate=str.isupper)
    kind: str = OneOf('wood', 'metal', 'plastic')
    quantity: int = Number(minvalue=0)

例子：

try:
    Component(name="Log", kind="wood", quantity=3)
except ValueError as e:
    print(e)
    
Expected <method 'isupper' of 'str' objects> to be true for 'Log'

c = Component(name="LOG", kind="wood", quantity=3)
[c.name, c.kind, c.quantity]
['LOG', 'wood', 3]

我發現它在處理充當具有許多描述符字段的數據容器的類時非常有用。