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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Network instance is optional in many classes, which requires lot of checking","articleBody":"With reference to #509 - lots of classes depend on an instance of `class Network` and have it as an attribute in order to communicate with the CAN bus. Examples are `SdoBase()`, `PdoBase()`, `NmtBase()` and others. Their constructor does not require a `Network` argument so the formal type of the attribute is `network: Optional[Network] = None`.\r\n\r\nThese attributes are set when a `RemoteNode()` is created and the reference to the network is injected from `RemoteNode.associate_network()`.\r\n\r\nThe effect of this is that we'll need a lot of checks all over the code to ensure network is properly set. E.g. as here from `class EmcyProducer`:\r\n\r\n```python\r\n    def send(self, code: int, register: int = 0, data: bytes = b\"\"):\r\n        payload = EMCY_STRUCT.pack(code, register, data)\r\n        if self.network is None:   # This is needed to not fail the send_message line\r\n            raise RuntimeError(\"A Network is required\")\r\n        self.network.send_message(self.cob_id, payload)\r\n```\r\n\r\nIs is a requirement to be able to create these class instances without a functional Network? We could make a default Network-like object that will emulate network operations if we need it to work without an actual CAN bus network.\r\n\r\nWhat do you think we should do here?","author":{"url":"https://github.com/sveinse","@type":"Person","name":"sveinse"},"datePublished":"2024-07-10T09:56:59.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":4},"url":"https://github.com/511/canopen/issues/511"}