fix(csharp,python)!: replace MqttLocalId inheritance with composition - #70
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…LSP violation Adds a failing test per language simulating a real-world function signature that accepts a LocalId parameter (exactly what happens when an MqttLocalId is passed as an argument, since it IS-A LocalId): the returned string is the MQTT format instead of the standard dnv-v2 format.
… inheriting LocalId BREAKING CHANGE: MqttLocalId no longer inherits from LocalId (C#) / is no longer a subclass of LocalId (Python). Code that upcasts MqttLocalId to LocalId, or checks `is LocalId`/`isinstance(x, LocalId)`, will no longer compile (C#) or will start returning False (Python). MqttLocalId publicly inherited from LocalId but produced a fundamentally incompatible ToString()/__str__() format (no leading slash, underscores, no meta/ section), violating Liskov substitution: a caller holding a LocalId reference could silently receive MQTT-topic text instead of the standard dnv-v2 format. MqttLocalId now composes a LocalIdBuilder directly. NamingRule/NAMING_RULE and members unused by the MQTT format (VerboseMode/HasCustomTag/MetadataTags) are reachable via .Builder/.builder instead of being duplicated.
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Hi,
MqttLocalIdoverridesToString()/__str__()with a format incompatible withLocalId.Passing one where a
LocalIdis expected silently corrupts any pipeline that round-trips through the string:LocalId.TryParse(mqttLocalId.ToString())fails.The first commit adds failing tests that demonstrate the issue directly.
Replaced inheritance with composition.
This is a breaking change:
MqttLocalIdis no longer assignable toLocalId(C#) / no longerisinstance-true against it (Python).Any project relying on that relationship will need updating.
See attached scripts and outputs for a concrete illustration:
cs_mqtt_lsp_violation.zip
py_mqtt_lsp_violation.zip
I looked at a less invasive fix first by keeping the inheritance (
sealed/newon the C# side to block the unsafe upcast) but dropped it because Python has no static dispatch, sostr()always calls the subclass's method regardless of the declared type, and I did not find a way to make both languages behave the same way.Composition was the only option I found that worked in both.