Python中利用描述符以及装饰器实现数据类型校验

 

Python和js相似是弱类型语言，对变量赋值没有没有严格意义限制；

以下通过描述符以及装饰器来实现对用户数据进行类型校验；

装饰器定义好类的属性类型，实例化时会在装饰器中校验People的name类型以及age类型

 

"""
    描述符：实现 __get__() __set()__ 任意两个函数
"""


class Typed:
    def __init__(self, key, valid_type):
        self.key = key
        self.valid_type = valid_type

    def __get__(self, instance, owner):
        return instance.__dict__[self.key]

    def __set__(self, instance, value):
        if not isinstance(value, self.valid_type):
            raise TypeError('Invalid data type, pls check')
        instance.__dict__[self.key] = value


def deco(**kwargs):
    def wrapper(obj):
        for key, val in kwargs.items():
            setattr(obj, key, Typed(key, val))
        return obj
    return wrapper


@deco(name=str, age=int)
class People:
    # name = Typed('name', str)
    def __init__(self, name, age):
        self.name = name
        self.age = age


p1 = People('louis', 18)
print(p1.__dict__)  # {'name': 'louis', 'age': 18}
p2 = People('scar', '24')  # TypeError: Invalid data type, pls check