Yaml.unsafe_load error

[Albert-Jan Roskam]

   Hi,
   I am trying to create a celery.schedules.crontab object from an external
   yaml file. I can successfully create an instance from a dummy class "Bar",
   but the crontab class seems call __setstate__ prior to __init__. I have no
   idea how to solve this. Any ideas? See code below.
   Thanks!
   Albert-Jan

   Python 3.6.8 (default, Nov 16 2020, 16:55:22)

   [GCC 4.8.5 20150623 (Red Hat 4.8.5-44)] on linux

   Type "help", "copyright", "credits" or "license" for more information.

   >>> import yaml

   >>> from celery.schedules import crontab

   >>> crontab(hour=3, minute=0)

   <crontab: 0 3 * * * (m/h/d/dM/MY)>

   >>> yaml.unsafe_load('!!python/name:celery.schedules.crontab')

   <class 'celery.schedules.crontab'>

   >>> yaml.safe_load('celery.schedules.crontab:\n   hour: 3\n   minute:
   0\n')

   {'celery.schedules.crontab': {'hour': 3, 'minute': 0}}

   >>> class Bar:

   ...     def __init__(self, x, y):

   ...         pass

   ...

   >>> bar = yaml.unsafe_load('!!python/object:__main__.Bar\n   x: 42\n   y:
   666')

   >>> bar

   <__main__.Bar object at 0x7f43b464bb38>

   >>> bar.x

   42

    

   # what is the correct way for the next line?

   >>> yaml.unsafe_load('!!python/object:celery.schedules.crontab\n   hour:
   3\n   minute: 30')

   Traceback (most recent call last):

     File "<stdin>", line 1, in <module>

     File
   "/home/albertjan at mycompany/envs/myenv/lib64/python3.6/site-packages/yaml/__init__.py",
   line 182, in unsafe_load

       return load(stream, UnsafeLoader)

     File
   "/home/albertjan at mycompany/envs/myenv/lib64/python3.6/site-packages/yaml/__init__.py",
   line 114, in load

       return loader.get_single_data()

     File
   "/home/albertjan at mycompany/envs/myenv/lib64/python3.6/site-packages/yaml/constructor.py",
   line 51, in get_single_data

       return self.construct_document(node)

     File
   "/home/albertjan at mycompany/envs/myenv/lib64/python3.6/site-packages/yaml/constructor.py",
   line 60, in construct_document

       for dummy in generator:

     File
   "/home/albertjan at mycompany/envs/myenv/lib64/python3.6/site-packages/yaml/constructor.py",
   line 621, in construct_python_object

       self.set_python_instance_state(instance, state)

     File
   "/home/albertjan at mycompany/envs/myenv/lib64/python3.6/site-packages/yaml/constructor.py",
   line 727, in set_python_instance_state

       instance, state, unsafe=True)

     File
   "/home/albertjan at mycompany/envs/myenv/lib64/python3.6/site-packages/yaml/constructor.py",
   line 597, in set_python_instance_state

       instance.__setstate__(state)

     File
   "/home/albertjan at mycompany/envs/myenv/lib/python3.6/site-packages/celery/schedules.py",
   line 541, in __setstate__

       super().__init__(**state)

   TypeError: __init__() got an unexpected keyword argument 'hour'