python-yaml檔案讀取的進階封裝

如下是對yaml解析器的進階封裝，使用了面向對象的思想。

demo.yml檔案中的内容：

test:
  a:
    b: dashuai
           

封裝代碼 

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):
        """通路不存在的屬性key時傳回None"""
        return None

    def __setattr__(self, key, value):
        """設定執行個體屬性值"""
        self[key] = value

    def __setitem__(self, key, value):
        """給self[key]指派"""
        super().__setattr__(key, value)
        super().__setitem__(key, value)

    def __missing__(self, key):
        """通路的鍵key不存在時，傳回None"""
        return None


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

    print(data.a)            # 調用__getattr__ 傳回None
    print(data['a'])         # 調用__missing__ 傳回None
           

說明：代碼中定義了YamlOperation類，繼承了dict字典，并重寫了幾個帶__的魔法方法。魔法方法的使用參考：python魔法方法、内置方法詳解，執行個體化類的對象後，可以用.屬性的方式通路。