feat: add EventBus.remove() to unsubscribe handlers

[HankGrimm]

What

Add a public EventBus.remove(event_pattern, handler) method so callers can unsubscribe a handler registered with EventBus.on(). Returns True if the handler was found and removed, False otherwise.

Also extract the event-key resolution from on() into _get_event_key() and reuse it in on() and remove(), and refactor expect() cleanup to use remove().

Why

There is no way to unsubscribe after EventBus.on() — the only cleanup path is expect()'s internal self.handlers[...].remove(...). Closes #5.

How tested

• Added tests/test_remove_handler.py (4 cases: by class, by string name, scoped removal, wildcard *).
• Core suite: 63 passed.

🤖 Generated with Claude Code

---

Summary by cubic

Adds EventBus.remove() to unsubscribe a handler registered with EventBus.on(). Returns True if the handler was found and removed, False otherwise. Closes #5.

Changes

• Extracts event-key resolution into _get_event_key() and reuses it in on(), remove(), and expect() cleanup.
• Adds tests covering removal by class, string name, scoped handlers, and * wildcard.

^{Written for commit 72b92d6. Summary will update on new commits.}

[cubic-dev-ai]

2 issues found across 2 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="bubus/service.py">

<violation number="1" location="bubus/service.py:456">
P3: After removing the last handler for an event key, the key remains in `self.handlers` as an empty list because the method never cleans up the entry. Since `handlers` is a `defaultdict(list)`, repeated remove()/expect() calls leave many empty keys, which accumulates over the bus lifetime and inflates `len(self.handlers)` shown in `__str__`. Delete the key when its list becomes empty.</violation>

<violation number="2" location="bubus/service.py:483">
P2: When a handler is typed for a concrete event, strict type checking rejects `remove(PingEvent, handler)` even though `on(PingEvent, handler)` accepts it. Add `remove()` overloads matching `on()` or otherwise preserve the handler's concrete event type.</violation>
</file>

<sub>Reply with feedback, questions, or to request a fix.

Fix all with cubic | Re-trigger cubic</sub>

[cubic-dev-ai]

P2: When a handler is typed for a concrete event, strict type checking rejects remove(PingEvent, handler) even though on(PingEvent, handler) accepts it. Add remove() overloads matching on() or otherwise preserve the handler's concrete event type.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At bubus/service.py, line 483:

<comment>When a handler is typed for a concrete event, strict type checking rejects `remove(PingEvent, handler)` even though `on(PingEvent, handler)` accepts it. Add `remove()` overloads matching `on()` or otherwise preserve the handler's concrete event type.</comment>

<file context>
@@ -482,6 +472,38 @@ def on(
+            return event_pattern.__name__  # pyright: ignore[reportUnknownMemberType, reportUnknownVariableType]
+        return str(event_pattern)
+
+    def remove(self, event_pattern: EventPatternType, handler: ContravariantEventHandler['BaseEvent[Any]']) -> bool:
+        """
+        Unsubscribe a previously registered handler from events matching a pattern.
</file context>

[cubic-dev-ai]

P3: After removing the last handler for an event key, the key remains in self.handlers as an empty list because the method never cleans up the entry. Since handlers is a defaultdict(list), repeated remove()/expect() calls leave many empty keys, which accumulates over the bus lifetime and inflates len(self.handlers) shown in __str__. Delete the key when its list becomes empty.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At bubus/service.py, line 456:

<comment>After removing the last handler for an event key, the key remains in `self.handlers` as an empty list because the method never cleans up the entry. Since `handlers` is a `defaultdict(list)`, repeated remove()/expect() calls leave many empty keys, which accumulates over the bus lifetime and inflates `len(self.handlers)` shown in `__str__`. Delete the key when its list becomes empty.</comment>

<file context>
@@ -453,17 +453,7 @@ def on(
-
-        # Ensure event_key is definitely a string at this point
-        assert isinstance(event_key, str)
+        event_key = self._get_event_key(event_pattern)
 
         # Check for duplicate handler names
</file context>