Pythonのレジストリパターン実装

scopedregistry.py

class Registry(object):
    instance = None

    @classmethod
    def initialize(cls):
        cls.instance = Registry()

    def __init__(self):
        self.data = 'Hello World'

    @classmethod
    def get_data(cls):
        if not cls.instance:
            cls.instance = Registry()
        return cls.instance.data


import threading

class ThreadRegistry(object):
    # threding.local()のデータはスコープを抜けると直ちにデストラクタが呼ばれる
    thread_local = threading.local()

    @classmethod
    def get_instance(cls):
        return cls.thread_local.instance

    @classmethod
    def initialize(cls, data):
        if not getattr(cls.thread_local, 'instance', None):
            cls.thread_local.instance = ThreadRegistry(data)

    def __init__(self, data):
        self.data = data

    def get_data(self):
        return self.data


if __name__ == '__main__':
    ThreadRegistry.initialize('thread 001')

    def call_thread(data):
        ThreadRegistry.initialize(data)
        for _ in range(20):
            print(ThreadRegistry.get_instance().get_data())

    th = threading.Thread(target=call_thread, args=['thread 002'])
    th.start()
    
    for _ in range(20):
        print(ThreadRegistry.get_instance().get_data())