python 單例

class CommonParams(object):
    '''
        沒有就進行實例化，有就從緩存中讀取
    '''
    instance = None

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

    @classmethod
    def getInstance(cls):
        if cls.instance:
            return cls.instance
        else:
            ...
            company_id = result_mst_company['company_id']
        obj = cls(company_id)
        cls.instance = obj
        return obj