Overriding generic method doesn't work.

General Issues and Bug Reporting
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Please select what you are reporting on:

Verse

What Type of Bug are you experiencing?

Verse

Summary

If i try to create a class that derives from listenable(t), i can not override the Subscribe function.

Steps to Reproduce

Copy paste this into a verse file:

# Base implementation for events on `creative_device`s.
device_event(t:type)<computes> := class<abstract>(listenable(t)):
    EventName<public>:[]char

# Partial implementation of `device_event(:type)` with no return payload.
device_event()<computes> := device_event(tuple())

# Implementation of `device_event(:type)` with required `agent` payload.
device_event_agent := class(device_event(agent)):
    # Subscribes Callback to this event. That same Callback will only be triggered once per event even if it is called with Subscribe more than once.
    Subscribe<override>(Callback:type {__(:agent):void})<transacts>:cancelable = Err()

    Await<override>()<suspends>:agent = Err()

The Subscribe override will show this error:

Using a value of type type{_(:agent->void)<transacts>:cancelable} as a value of type type{_(:any->void)<transacts>:cancelable} is not yet implemented.(3502)

However this is clearly supposed to work. It also works in the VerseDevices.Digest.verse file, where we have this:

    # Base implementation for events on `creative_device`s.
    device_event<native><epic_internal>(t:type)<computes> := class<abstract>(listenable(t)):
        EventName<native><public>:[]char

    # Partial implementation of `device_event(:type)` with no return payload.
    device_event<epic_internal>()<computes> := device_event(tuple())

    # Implementation of `device_event(:type)` with no payload.
    device_event_void<native><epic_internal> := class(device_event(tuple())):
        # Subscribes Callback to this event. That same Callback will only be triggered once per event even if it is called with Subscribe more than once.
        Subscribe<native><override>(Callback:type {__():void})<transacts>:cancelable

        Await<native><override>()<suspends>:tuple()

    # Implementation of `device_event(:type)` with required `agent` payload.
    device_event_agent<native><epic_internal> := class(device_event(agent)):
        # Subscribes Callback to this event. That same Callback will only be triggered once per event even if it is called with Subscribe more than once.
        Subscribe<native><override>(Callback:type {__(:agent):void})<transacts>:cancelable

        Await<native><override>()<suspends>:agent

Expected Result

It should work without error.

Observed Result

It errors.

Platform(s)

All

2

UCB-1230 incident has been created. Status is ‘Awaiting Validation’.