求更简洁优雅的Python条件返回处理器实现方案

优化方案1：用映射字典统一管理逻辑 #

def _get_handler_by_topic_arn(topic_arn: str, event_name: str, event_message: dict):
    # 建立topic ARN与处理器、过滤条件的映射
    topic_map = {
        CONFIG.get("MT_MAIN_SNS_TOPIC_ARN"): (MT_MAIN_TOPIC_HANDLERS, lambda msg: True),
        CONFIG.get("FOX_REQUEST_SNS_TOPIC_ARN"): (FOX_REQUEST_TOPIC_HANDLERS, lambda msg: True),
        CONFIG.get("FOX_ORDER_RESULTS_SNS_TOPIC_ARN"): (
            FOX_ORDER_RESULTS_TOPIC_HANDLERS,
            lambda msg: not (msg.get("status") and msg.get("status") != "CANCELLED")
        )
    }

    handler_info = topic_map.get(topic_arn)
    if handler_info:
        handlers, check_condition = handler_info
        if check_condition(event_message):
            return handlers.get(event_name)
    return None

优化方案2：全局初始化映射（性能更优） #

如果该函数会被频繁调用，建议把映射移到函数外初始化，避免重复创建字典：

# 全局初始化topic配置映射（仅执行一次）
TOPIC_HANDLER_MAPPING = {
    CONFIG.get("MT_MAIN_SNS_TOPIC_ARN"): {
        "handlers": MT_MAIN_TOPIC_HANDLERS,
        "condition": lambda msg: True
    },
    CONFIG.get("FOX_REQUEST_SNS_TOPIC_ARN"): {
        "handlers": FOX_REQUEST_TOPIC_HANDLERS,
        "condition": lambda msg: True
    },
    CONFIG.get("FOX_ORDER_RESULTS_SNS_TOPIC_ARN"): {
        "handlers": FOX_ORDER_RESULTS_TOPIC_HANDLERS,
        "condition": lambda msg: not (msg.get("status") and msg.get("status") != "CANCELLED")
    }
}

def _get_handler_by_topic_arn(topic_arn: str, event_name: str, event_message: dict):
    topic_config = TOPIC_HANDLER_MAPPING.get(topic_arn)
    if topic_config and topic_config["condition"](event_message):
        return topic_config["handlers"].get(event_name)
    return None

优化思路说明 #

1. 替换链式if判断：用字典映射实现O(1)时间复杂度的查找，比原代码的O(n)更高效，后续新增topic时只需在映射中添加条目，无需修改函数逻辑
2. 统一处理过滤条件：把每个topic的特殊判断逻辑封装成条件函数，与处理器绑定，逻辑更清晰，扩展性更强
3. 减少重复操作：方案2将映射全局初始化，避免每次调用函数都重新构建字典，进一步提升性能

内容的提问来源于stack exchange，提问作者Asthonishia