Sprouts and mature nodes need a single attribute for the value of "domain"

[derekpierre]

The following occurs on the network status monitor which uses forgetful node storage:

File "/Users/derek/Documents/Github/repos/monitor/nucypher-monitor/monitor/crawler.py", line 328, in learn_from_teacher_node
    new_nodes = super().learn_from_teacher_node(*args, **kwargs)
  File "/Users/derek/.local/share/virtualenvs/nucypher-monitor-3hnjUmmD/lib/python3.7/site-packages/nucypher/network/nodes.py", line 764, in learn_from_teacher_node
    remembered_seednodes = self.load_seednodes(record_fleet_state=False)
  File "/Users/derek/.local/share/virtualenvs/nucypher-monitor-3hnjUmmD/lib/python3.7/site-packages/nucypher/network/nodes.py", line 339, in load_seednodes
    nodes_restored_from_storage = self.read_nodes_from_storage() if read_storage else []
  File "/Users/derek/.local/share/virtualenvs/nucypher-monitor-3hnjUmmD/lib/python3.7/site-packages/nucypher/network/nodes.py", line 353, in read_nodes_from_storage
    node_domain = node.domain.decode('utf-8')
builtins.AttributeError: 'Ursula' object has no attribute 'domain'

Discord conversation:

derek09/29/2020
@dnunez it's forgetful. It's the monitor's SQLiteForgetfulStorage

dnunez09/29/2020
Right.... So that must be it
The type of nodes that storages fetch are different. That's actually not a good API...

...

dnunez09/30/2020
@jMyles @derek the thing is that sprouts have domain but matured nodes don't, as they use it to construct the serving_domain attribute. Maybe we should simplify that and just have domain ?

jMyles09/30/2020
Absolutely.
For a primordial variant of a polymorhpic class to have an attribute that is not either an attribute or a method on a commensurate evolved variant is an antipattern.
In my opinion.

derek09/30/2020
:thumbsup: Agreed!

[derekpierre]

@cygnusv running into the related problem with the status monitor using nucypher 3.0.0b4. Instead of domain it is now learning_domain.

  File "/Users/derek/.local/share/virtualenvs/nucypher-monitor-3hnjUmmD/lib/python3.7/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/Users/derek/.local/share/virtualenvs/nucypher-monitor-3hnjUmmD/lib/python3.7/site-packages/nucypher/cli/options.py", line 163, in wrapper
    return func(**kwargs)
  File "/Users/derek/Documents/Github/repos/monitor/nucypher-monitor/monitor/cli/main.py", line 96, in crawl
    influx_port=influx_port)
  File "/Users/derek/Documents/Github/repos/monitor/nucypher-monitor/monitor/crawler.py", line 261, in __init__
    *args, **kwargs)
  File "/Users/derek/.local/share/virtualenvs/nucypher-monitor-3hnjUmmD/lib/python3.7/site-packages/nucypher/network/nodes.py", line 251, in __init__
    self.remember_node(node, eager=True)
  File "/Users/derek/.local/share/virtualenvs/nucypher-monitor-3hnjUmmD/lib/python3.7/site-packages/nucypher/network/nodes.py", line 393, in remember_node
    self.node_storage.store_node_metadata(node=node)
  File "/Users/derek/Documents/Github/repos/monitor/nucypher-monitor/monitor/crawler.py", line 58, in store_node_metadata
    self.__write_node_metadata(node)
  File "/Users/derek/Documents/Github/repos/monitor/nucypher-monitor/monitor/crawler.py", line 98, in __write_node_metadata
    node_dict = node.node_details(node=node)
  File "/Users/derek/.local/share/virtualenvs/nucypher-monitor-3hnjUmmD/lib/python3.7/site-packages/nucypher/network/nodes.py", line 1385, in node_details
    "domain": node.learning_domain,
AttributeError: 'Ursula' object has no attribute 'learning_domain'