Python类中嵌套对象属性的设置与管理：字典与自定义类的应用

class Example:
    def __init__(self, a, b):
        self.a = a
        self.sub_obj = {}  # sub_obj 是一个字典
        self.sub_obj.b = b # 错误：字典没有名为'b'的属性

class Example:
    def __init__(self, a, b):
        self.a = a
        # 正确：将'b'作为键，b的值作为其对应的值，初始化字典
        self.sub_obj = {'b': b} 

    def update_b(self, new_b):
        """
        更新sub_obj中键'b'的值。
        """
        self.sub_obj['b'] = new_b

# 示例使用
obj = Example('hi', 'hello')

# 访问顶级属性
print(f"obj.a: {obj.a}") # 输出: obj.a: hi

# 访问嵌套字典的键
print(f"obj.sub_obj['b']: {obj.sub_obj['b']}") # 输出: obj.sub_obj['b']: hello

# 更新嵌套字典的键
obj.update_b('world')
print(f"obj.sub_obj['b'] after update: {obj.sub_obj['b']}") # 输出: obj.sub_obj['b'] after update: world

# 如果需要，也可以直接通过实例访问并修改字典键
obj.sub_obj['c'] = 123
print(f"obj.sub_obj: {obj.sub_obj}") # 输出: obj.sub_obj: {'b': 'world', 'c': 123}

import json

class UserProfile:
    def __init__(self, name, email, city, country):
        self.name = name
        self.contact_info = {
            'email': email,
            'address': {
                'city': city,
                'country': country
            }
        }

user = UserProfile('Alice', 'alice@example.com', 'New York', 'USA')

# 将对象转换为字典（通常通过__dict__或自定义方法）
# 注意：直接json.dumps(user)会报错，需要先转换为可序列化的字典
user_dict = {
    'name': user.name,
    'contact_info': user.contact_info
}

json_output = json.dumps(user_dict, indent=4)
print(json_output)

{
    "name": "Alice",
    "contact_info": {
        "email": "alice@example.com",
        "address": {
            "city": "New York",
            "country": "USA"
        }
    }
}

class ContactInfo:
    def __init__(self, email, phone=None):
        self.email = email
        self.phone = phone

    def send_email(self, subject, body):
        print(f"Sending email to {self.email} with subject '{subject}'")

class Person:
    def __init__(self, name, email, phone=None):
        self.name = name
        # sub_obj 现在是一个 ContactInfo 类的实例
        self.contact = ContactInfo(email, phone) 

# 示例使用
person = Person('Bob', 'bob@example.com', '123-456-7890')

print(f"Person name: {person.name}")
print(f"Person email: {person.contact.email}") # 通过点运算符访问子对象的属性
person.contact.send_email("Meeting", "Please confirm your attendance.")