import a class method from file as static in python

Question

Actually, I couldn't find a proper topic. I'm trying to use the Apscheduler library. I created a class method for the library and added some missing features by myself as a whole new scheduler library. When using an SQLAlchemyJobStore the added functions to scheduler must be serializable but as I created a new class the added functions are members of the class itself. For example, suppose this code:

from datetime import datetime
from time import sleep
from apscheduler.schedulers.background import BackgroundScheduler
from apscheduler.jobstores.sqlalchemy import SQLAlchemyJobStore


class sched:
    def __init__(self):
        jobstores = {
            'default': SQLAlchemyJobStore(url='sqlite:///test.db')
        }
        self.scheduler = BackgroundScheduler(jobstores=jobstores)

    def add_func(self, some_func, args={}, kwargs={}):
        self.scheduler.add_job(
            some_func, 'interval', args=args, kwargs=kwargs, seconds=5, replace_existing=True)

    def start(self):
        self.scheduler.start()


    def tick(self, i, j, **kwargs):
        print("hello{} {}".format(i, j))
        for k in kwargs:
            print(k, ":", kwargs[k])

if __name__ == '__main__':
    schedule = sched()
    schedule.start()
    schedule.add_func(schedule.tick, args=[1, 2], kwargs=dict(a=1, b=2))
    # using the following three lines solve the problem
    # sched = sched()
    # sched.start()
    # sched.add_func(sched.tick, args=[1, 2], kwargs=dict(a=1, b=2))
    while True:
        sleep(.1)

Traceback (most recent call last): File "...\Python36\lib\site-packages\apscheduler\executors\base.py", line 125, in run_job retval = job.func(*job.args, **job.kwargs) TypeError: tick() missing 1 required positional argument: 'j'

This error means the whole class cannot be serialized but if I name my instance same as class name (here sched) it would be fixed. In the example, the tick function must be a member of schedule class itself because in my original class scheduler.add_job gets a modified function from the class methods and currently, I don't want to edit my new schedule class entirely.

My question is when I want to import the class from a file the exact problem happens. Is there any other way to just import the class from a file?

Answer 1

Because the whole class sched cannot be serialized in Database, class MUST be defined as static. So I changed the class to static class.

from datetime import datetime
from time import sleep
from apscheduler.schedulers.background import BackgroundScheduler
from apscheduler.jobstores.sqlalchemy import SQLAlchemyJobStore


class sched:
    jobstores = {
        'default': SQLAlchemyJobStore(url='sqlite:///test.db')
    }
    scheduler = BackgroundScheduler(jobstores=jobstores)
    @classmethod
    def add_func(cls, some_func, args={}, kwargs={}):
        cls.scheduler.add_job(
            some_func, 'interval', args=args, kwargs=kwargs, seconds=5, replace_existing=True)

    @classmethod
    def start(cls):
        cls.scheduler.start()

    @classmethod
    def tick(cls, i, j, **kwargs):
        print("hello{} {}".format(i, j))
        for k in kwargs:
            print(k, ":", kwargs[k])

if __name__ == '__main__':
    schedule = sched()
    schedule.start()
    schedule.add_func(schedule.tick, args=[1, 2], kwargs=dict(a=1, b=2))
    while True:
        sleep(.1)