ee.event_names (#99)

* Class Decorator API (#84)

* Add class decorator API

* Add autofunctions for pyee.cls

* Remove travis file

* docs: Fix a few typos (#91)

* Type Annotations (#97)

* Set up virtualenv, pyright and isort

* Run isort

* Passing type annotations for base.py

* action to run type checks

* Alas!

* Happy type checker for trio

* MOST of the library is type-checking

* working, non-cranky type annotations for uplift laul

* Type check the tests, cause an explosion

* Clean up requirements.txt

* tests type-checking

* py.typed file

* tests and linting happy

* Update build

* obvious action bugfix

* trailing comma

* remove inconsequential and angry type annotation

* Ignore type issues w asyncio import

* messy typecast

* anyway thats when I started blasting

* carnage!

* uplift bugfixes

* update pytest

* bye 3.6

* type annotations for cls

Co-authored-by: Tim Gates <tim.gates@iress.com>

* added function that returns an array listing the events

* ee.event_names tested and passing

Now that there are some asserts for the value of event_names, we can see
what issue @leirons was running into with `new_listener`. It turns out
the issue ran pretty deep.

Internally, pyee used to use a defaultdict to store events. This was
mildly convenient for implementing on and emit, but it also meant that
event names were added after an emit, even if there were no handlers.

OK, so you patch it to use a regular dict and do the bookkeeping
manually. But there's another reason an event might show up even if it
has no handlers: pyee doesn't make an effort to clean up the
OrderedDicts which contain the actual handlers.

To solve this, I removed the defaultdict (so no event after an
emit) and added a step on listener removal to clean up the OrderedDict.

* Make event_names return a set instead of a list

Co-authored-by: Tim Gates <tim.gates@iress.com>
Co-authored-by: Ivan <grecigor11@gmail.com>

pyee/base.py

@@ -1,8 +1,8 @@
 # -*- coding: utf-8 -*-
 
-from collections import defaultdict, OrderedDict
+from collections import OrderedDict
 from threading import Lock
-from typing import Any, Callable, Dict, List, Optional, Tuple
+from typing import Any, Callable, Dict, List, Optional, Set, Tuple
 
 
 class PyeeException(Exception):
@@ -44,7 +44,7 @@ def __init__(self) -> None:
         self._events: Dict[
             str,
             "OrderedDict[Callable, Callable]",
-        ] = defaultdict(OrderedDict)
+        ] = dict()
         self._lock: Lock = Lock()
 
     def on(self, event: str, f: Optional[Callable] = None) -> Callable:
@@ -110,6 +110,8 @@ def _add_event_handler(self, event: str, k: Callable, v: Callable):
         # different for `once` handlers, where v is a wrapped version
         # of k which removes itself before calling k
         with self._lock:
+            if event not in self._events:
+                self._events[event] = OrderedDict()
             self._events[event][k] = v
 
     def _emit_run(
@@ -120,6 +122,10 @@ def _emit_run(
     ) -> None:
         f(*args, **kwargs)
 
+    def event_names(self) -> Set[str]:
+        """Get a list of events that this emitter is listening to."""
+        return set(self._events.keys())
+
     def _emit_handle_potential_error(self, event: str, error: Any) -> None:
         if event == "error":
             if isinstance(error, Exception):
@@ -136,7 +142,7 @@ def _call_handlers(
         handled = False
 
         with self._lock:
-            funcs = list(self._events[event].values())
+            funcs = list(self._events.get(event, OrderedDict()).values())
         for f in funcs:
             self._emit_run(f, args, kwargs)
             handled = True
@@ -203,6 +209,8 @@ def g(
     def _remove_listener(self, event: str, f: Callable) -> None:
         """Naked unprotected removal."""
         self._events[event].pop(f)
+        if not len(self._events[event]):
+            del self._events[event]
 
     def remove_listener(self, event: str, f: Callable) -> None:
         """Removes the function ``f`` from ``event``."""
@@ -217,7 +225,7 @@ def remove_all_listeners(self, event: Optional[str] = None) -> None:
             if event is not None:
                 self._events[event] = OrderedDict()
             else:
-                self._events = defaultdict(OrderedDict)
+                self._events = dict()
 
     def listeners(self, event: str) -> List[Callable]:
         """Returns a list of all listeners registered to the ``event``."""

tests/test_sync.py

@@ -22,6 +22,8 @@ def event_handler(data, **kwargs):
         call_me()
         assert data == "emitter is emitted!"
 
+    assert ee.event_names() == {"event"}
+
     # Making sure data is passed propers
     ee.emit("event", "emitter is emitted!", error=False)
 
@@ -43,6 +45,8 @@ def test_emit_error():
     def on_error(exc):
         call_me()
 
+    assert ee.event_names() == {"error"}
+
     # No longer raises and error instead return True indicating handled
     assert ee.emit("error", test_exception) is True
     call_me.assert_called_once()
@@ -56,6 +60,8 @@ def test_emit_return():
     call_me = Mock()
     ee = EventEmitter()
 
+    assert ee.event_names() == set()
+
     # make sure emitting without a callback returns False
     assert not ee.emit("data")
 
@@ -79,6 +85,8 @@ def test_new_listener_event():
     def event_handler(data):
         pass
 
+    assert ee.event_names() == {"new_listener", "event"}
+
     call_me.assert_called_once_with("event", event_handler)
 
 
@@ -106,6 +114,8 @@ def fourth():
 
     ee.on("event", fourth)
 
+    assert ee.event_names() == {"event"}
+
     assert ee._events["event"] == OrderedDict(
         [(first, first), (second, second), (third, third), (fourth, fourth)]
     )
@@ -120,7 +130,7 @@ def fourth():
     assert ee._events["event"] == OrderedDict([(third, third), (fourth, fourth)])
 
     ee.remove_all_listeners("event")
-    assert ee._events["event"] == OrderedDict()
+    assert "event" not in ee._events["event"]
 
 
 def test_listener_removal_on_emit():
@@ -137,6 +147,8 @@ def should_remove():
     ee.on("remove", should_remove)
     ee.on("remove", call_me)
 
+    assert ee.event_names() == {"remove"}
+
     ee.emit("remove")
 
     call_me.assert_called_once()
@@ -148,6 +160,8 @@ def should_remove():
     ee.on("remove", call_me)
     ee.on("remove", should_remove)
 
+    assert ee.event_names() == {"remove"}
+
     ee.emit("remove")
 
     call_me.assert_called_once()
@@ -169,11 +183,15 @@ def once_handler(data):
     # Tests to make sure that after event is emitted that it's gone.
     ee.once("event", once_handler)
 
+    assert ee.event_names() == {"event"}
+
     ee.emit("event", "emitter is emitted!")
 
     call_me.assert_called_once()
 
-    assert ee._events["event"] == OrderedDict()
+    assert ee.event_names() == set()
+
+    assert "event" not in ee._events
 
 
 def test_once_removal():
@@ -187,10 +205,12 @@ def once_handler(data):
     handle = ee.once("event", once_handler)
 
     assert handle == once_handler
+    assert ee.event_names() == {"event"}
 
     ee.remove_listener("event", handle)
 
-    assert ee._events["event"] == OrderedDict()
+    assert "event" not in ee._events
+    assert ee.event_names() == set()
 
 
 def test_listeners():