python-yaml文件读取的高级封装

如下是对yaml解析器的高级封装，使用了面向对象的思想。

demo.yml文件中的内容：

test:
  a:
    b: dashuai
           

封装代码 

import yaml


class YamlOperation(dict):
    def __init__(self, file_path=None, content=None):
        super().__init__()

        if file_path is not None:
            with open(file_path, "r")as file:
                content = yaml.load(file, Loader=yaml.SafeLoader)

        content = content if content is not None else {}
        # content = [content, {}][not content]
        # content = (not content and content or {})

        for key, value in content.items():
            if isinstance(value, dict):
                self[key] = YamlOperation(content=value)
            else:
                self[key] = value

    def __getattr__(self, key):
        """访问不存在的属性key时返回None"""
        return None

    def __setattr__(self, key, value):
        """设置实例属性值"""
        self[key] = value

    def __setitem__(self, key, value):
        """给self[key]赋值"""
        super().__setattr__(key, value)
        super().__setitem__(key, value)

    def __missing__(self, key):
        """访问的键key不存在时，返回None"""
        return None


if __name__ == '__main__':
    data = YamlOperation("demo.yml")
    print(data.test)         # 输出：{'a': {'b': 'dashuai'}}
    print(data['test'])      # 输出：{'a': {'b': 'dashuai'}}
    print(data.get('test'))  # 输出：{'a': {'b': 'dashuai'}}
    print(data.test.a.b)     # 输出：dashuai

    print(data.a)            # 调用__getattr__ 返回None
    print(data['a'])         # 调用__missing__ 返回None
           

说明：代码中定义了YamlOperation类，继承了dict字典，并重写了几个带__的魔法方法。魔法方法的使用参考：python魔法方法、内置方法详解，实例化类的对象后，可以用.属性的方式访问。