Python模块类型提示与不可变配置管理实践

# src/payment_settings.py
from utils.payment import get_current_payment_settings

def __getattr__(name):
    """
    动态获取配置属性。
    """
    settings = get_current_payment_settings()
    return getattr(settings, name)

def __setattr__(name, value):
    """
    阻止对配置属性的修改，使其只读。
    """
    raise NotImplementedError("payment_settings 是只读的")

# src/another_file.py
from . import payment_settings

print(payment_settings.something)

# 定义获取当前支付设置的辅助函数（示例）
class CurrentPaymentSettings:
    def __init__(self):
        self._something = 123
        self._another_setting = "value"

    @property
    def something(self) -> int:
        return self._something

    @property
    def another_setting(self) -> str:
        return self._another_setting

def get_current_payment_settings_instance() -> CurrentPaymentSettings:
    # 实际应用中可能从数据库、文件等加载
    return CurrentPaymentSettings()

# src/payment_settings.py (改进版)
class PaymentSettings:
    """
    封装支付设置的类，通过属性提供只读访问。
    """
    def __init__(self):
        # 实际加载逻辑应在此处或由工厂方法处理
        self._settings = get_current_payment_settings_instance()

    @property
    def something(self) -> int:
        """获取 'something' 设置。"""
        return self._settings.something

    @property
    def another_setting(self) -> str:
        """获取 'another_setting' 设置。"""
        return self._settings.another_setting

# 实例化配置对象，以便在其他模块中导入和使用
payment_settings = PaymentSettings()

# src/another_file.py
from .payment_settings import payment_settings

print(payment_settings.something)
# print(payment_settings.non_existent_attribute) # 类型检查器会报错

from dataclasses import dataclass

# 定义实际的配置数据结构
@dataclass(frozen=True)
class _PaymentSettingsData:
    """
    内部使用的不可变支付设置数据结构。
    """
    something: int = 123
    another_setting: str = "default_value"

# 实例化配置对象
# 在实际应用中，_PaymentSettingsData的实例可能通过工厂函数或加载器创建
PaymentSettings = _PaymentSettingsData(something=456, another_setting="configured_value")

# src/another_file.py
from .payment_settings import PaymentSettings

print(PaymentSettings.something)
# PaymentSettings.something = 789 # 尝试修改会抛出FrozenInstanceError

from pydantic import BaseModel, ConfigDict

# 定义一个基础的不可变模型
class BaseImmutable(BaseModel):
    model_config = ConfigDict(frozen=True) # 启用不可变特性

# 定义嵌套的配置项（如果需要）
class NestedSettings(BaseImmutable):
    """嵌套配置示例。"""
    attr: int = 100

# 定义主支付设置模型
class _PaymentSettingsModel(BaseImmutable):
    """
    使用Pydantic定义的支付设置模型。
    """
    something: int = 123
    another_setting: str = "default_value"
    complex_option: NestedSettings = NestedSettings() # 包含嵌套配置

# 实例化配置对象
# 实际应用中，数据可能从JSON、YAML等加载并传递给Pydantic模型
PaymentSettings = _PaymentSettingsModel(
    something=789,
    another_setting="pydantic_value",
    complex_option=NestedSettings(attr=200)
)

# src/another_file.py
from .payment_settings import PaymentSettings

print(PaymentSettings.something)
print(PaymentSettings.complex_option.attr)
# PaymentSettings.something = 999 # 尝试修改会抛出ValidationError