Python实现字典的点号取值的三种常用方式

class DotDict(dict):
    """支持点号取值的字典类"""
    __getattr__ = dict.get
    __setattr__ = dict.__setitem__
    __delattr__ = dict.__delitem__

# 使用示例
d = DotDict({"name": "Alice", "age": 30, "address": {"city": "Shanghai"}})

print(d.name)          # 输出: Alice
print(d.address.city)  # 输出: Shanghai

d.job = "Engineer"     # 添加新属性
print(d.job)           # 输出: Engineer

class DotDict(dict):
    """支持嵌套字典的点号访问"""
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        for key, value in self.items():
            if isinstance(value, dict):
                self[key] = DotDict(value)
    
    def __getattr__(self, name):
        try:
            value = self[name]
            if isinstance(value, dict) and not isinstance(value, DotDict):
                return DotDict(value)
            return value
        except KeyError:
            raise AttributeError(f"'{self.__class__.__name__}' object has no attribute '{name}'")
    
    __setattr__ = dict.__setitem__
    __delattr__ = dict.__delitem__

# 使用示例
data = {
    "user": {
        "name": "Bob",
        "preferences": {
            "theme": "dark",
            "notifications": True
        }
    }
}

d = DotDict(data)
print(d.user.name)                   # 输出: Bob
print(d.user.preferences.theme)      # 输出: dark
d.user.preferences.font_size = 14    # 添加嵌套属性

class ReadOnlyDotDict(dict):
    """只读的点号访问字典"""
    def __getattr__(self, name):
        if name in self:
            value = self[name]
            if isinstance(value, dict):
                return ReadOnlyDotDict(value)
            return value
        raise AttributeError(f"No attribute '{name}'")
    
    def __setattr__(self, name, value):
        raise TypeError("'ReadOnlyDotDict' object is read-only")

# 使用示例
config = ReadOnlyDotDict({"api": {"url": " "timeout": 30}})
print(config.api.url)  # 输出: 
config.api.port = 8080 # 抛出 TypeError

# 实际应用示例 - 加载配置文件
import json
from dot_dict import DotDict  # 假设保存为 dot_dict.py

with open('config.json') as f:
    config = DotDict(json.load(f))

# 点号访问配置项
print(f"API端点: {config.api.base_url}")
print(f"超时设置: {config.api.timeout}s")