Merge #402

402: Pull event name transformation into engine. r=astronouth7303 a=pathunstrom

Closes #390 

Co-authored-by: Piper Thunstrom <[email protected]>

ppb/engine.py

@@ -1,8 +1,8 @@
+import time
 from collections import defaultdict
 from collections import deque
 from contextlib import ExitStack
 from itertools import chain
-import time
 from typing import Any
 from typing import Callable
 from typing import DefaultDict
@@ -11,19 +11,33 @@
 from typing import Union
 
 from ppb import events
-from ppb.eventlib import EventMixin
+from ppb.assetlib import AssetLoadingSystem
+from ppb.errors import BadEventHandlerException
 from ppb.systems import EventPoller
 from ppb.systems import Renderer
-from ppb.systems import Updater
 from ppb.systems import SoundController
-from ppb.assetlib import AssetLoadingSystem
+from ppb.systems import Updater
 from ppb.utils import LoggingMixin
-
+from ppb.utils import camel_to_snake
 
 _ellipsis = type(...)
 
+_cached_handler_names = {}
+
 
-class GameEngine(EventMixin, LoggingMixin):
+def _get_handler_name(txt):
+    result = _cached_handler_names.get(txt)
+    if result is None:
+        result = "on_" + camel_to_snake(txt)
+        _cached_handler_names[txt] = result
+    return result
+
+
+for x in events.__all__:
+    _get_handler_name(x)
+
+
+class GameEngine(LoggingMixin):
 
     def __init__(self, first_scene: Type, *,
                  basic_systems=(Renderer, Updater, EventPoller, SoundController, AssetLoadingSystem),
@@ -127,17 +141,26 @@ def publish(self):
         scene = self.current_scene
         event.scene = scene
         extensions = chain(self.event_extensions[type(event)], self.event_extensions[...])
+
+        # Hydrating extensions.
         for callback in extensions:
             callback(event)
-        self.__event__(event, self.signal)
-        for system in self.systems:
-            system.__event__(event, self.signal)
-        # Required for if we publish with no current scene.
-        # Should only happen when the last scene stops via event.
-        if scene is not None:
-            scene.__event__(event, self.signal)
-            for game_object in scene:
-                game_object.__event__(event, self.signal)
+
+        event_handler_name = _get_handler_name(type(event).__name__)
+        for obj in self.walk():
+            method = getattr(obj, event_handler_name, None)
+            if callable(method):
+                try:
+                    method(event, self.signal)
+                except TypeError as ex:
+                    from inspect import signature
+                    sig = signature(method)
+                    try:
+                        sig.bind(event, self.signal)
+                    except TypeError:
+                        raise BadEventHandlerException(obj, event_handler_name, event) from ex
+                    else:
+                        raise
 
     def on_start_scene(self, event: events.StartScene, signal: Callable[[Any], None]):
         """
@@ -212,3 +235,10 @@ def flush_events(self):
         the wrong scene.
         """
         self.events = deque()
+
+    def walk(self):
+        yield self
+        yield from self.systems
+        yield self.current_scene
+        if self.current_scene is not None:
+            yield from self.current_scene

ppb/errors.py

@@ -0,0 +1,25 @@
+class BadEventHandlerException(TypeError):
+
+    def __init__(self, instance, method, event):
+        object_type = type(instance)
+        event_type = type(event)
+        o_name = object_type.__name__
+        e_name = event_type.__name__
+        article = ['a', 'an'][int(e_name.lower()[0] in "aeiou")]
+
+        message = f"""
+{o_name}.{method}() signature incorrect, it should accept {article} {e_name} object and a signal function.
+
+{e_name} is a dataclass that represents an event. Its attributes 
+tell you about the event.
+
+The signal function is a function you can call that accepts an event instance
+as its only parameter. Call it to add an event to the queue. You don't have to
+use it, but it is a mandatory argument provided by ppb.
+
+It should look like this:
+
+def {method}({e_name.lower()}_event: {e_name}, signal_function):
+    (Your code goes here.)
+"""
+        super().__init__(message)

ppb/features/twophase.py

@@ -3,7 +3,6 @@
 """
 from dataclasses import dataclass
 from ppb.systemslib import System
-from ppb.eventlib import EventMixin
 
 __all__ = 'Commit',
 
@@ -24,7 +23,7 @@ def on_update(self, event, signal):
         signal(Commit())
 
 
-class TwoPhaseMixin(EventMixin):
+class TwoPhaseMixin:
     """
     Mixin to apply to objects to handle two phase updates.
     """

ppb/scenes.py

@@ -9,7 +9,6 @@
 from typing import Type
 
 from ppb.camera import Camera
-from ppb.eventlib import EventMixin
 
 
 class GameObjectCollection(Collection):
@@ -96,7 +95,7 @@ def remove(self, game_object: Hashable) -> None:
             s.discard(game_object)
 
 
-class BaseScene(EventMixin):
+class BaseScene:
     # Background color, in RGB, each channel is 0-255
     background_color: Sequence[int] = (0, 0, 100)
     container_class: Type = GameObjectCollection

ppb/sprites.py

@@ -15,7 +15,6 @@
 from ppb_vector import Vector
 
 import ppb
-from ppb.eventlib import EventMixin
 from ppb.utils import FauxFloat
 
 __all__ = (
@@ -35,7 +34,7 @@
 side_attribute_error_message = error_message.format
 
 
-class BaseSprite(EventMixin):
+class BaseSprite:
     """
     The base Sprite class. All sprites should inherit from this (directly or
     indirectly).

ppb/systemslib.py

@@ -1,7 +1,4 @@
-from ppb import eventlib
-
-
-class System(eventlib.EventMixin):
+class System:
 
     def __init__(self, **_):
         pass

ppb/utils.py

@@ -1,9 +1,10 @@
 import logging
-import sys
-import numbers
 import math
+import numbers
+import re
+import sys
 
-__all__ = 'LoggingMixin', 'FauxFloat',
+__all__ = 'LoggingMixin', 'FauxFloat', 'camel_to_snake'
 
 
 # Dictionary mapping file names -> module names
@@ -22,6 +23,15 @@ def _build_index():
     }
 
 
+_boundaries_finder = re.compile('(.)([A-Z][a-z]+)')
+_boundaries_finder_2 = re.compile('([a-z0-9])([A-Z])')
+
+
+def camel_to_snake(txt):
+    s1 = _boundaries_finder.sub(r'\1_\2', txt)
+    return _boundaries_finder_2.sub(r'\1_\2', s1).lower()
+
+
 def _get_module(file_name):
     """
     Find the module name for the given file name, or raise KeyError if it's

tests/test_events.py

@@ -1,62 +1,8 @@
 from pytest import mark
 from pytest import raises
 
-from ppb.eventlib import BadEventHandlerException
-from ppb.eventlib import camel_to_snake
-from ppb.eventlib import EventMixin
-
-
-def test_eventmixin():
-    passed_bag = None
-    passed_fire = None
-
-    class Spam:
-        pass
-
-    class Eventable(EventMixin):
-        def on_spam(self, bag, fire_event):
-            nonlocal passed_bag, passed_fire
-            passed_fire = fire_event
-            passed_bag = bag
-
-    bag = Spam()
-    fire_event = lambda: None
-
-    e = Eventable()
-
-    e.__event__(bag, fire_event)
-    assert bag is passed_bag
-    assert fire_event is passed_fire
-
-
-def test_event_mixin_with_bad_signature():
-
-    class BadSpam:
-        pass
-
-
-    class Spam:
-        pass
-
-
-    class Eventable(EventMixin):
-        def on_spam(self, spam_event):
-            pass
-
-        def on_bad_spam(self, bad_spam_event, signal):
-            raise TypeError
-
-    e = Eventable()
-
-    with raises(BadEventHandlerException):
-        e.__event__(Spam(), lambda x: None)
-
-    with raises(TypeError) as exception_info:
-        e.__event__(BadSpam(), lambda x: None)
-
-    exec = exception_info.value
-    assert not isinstance(exec, BadEventHandlerException)
-
+from ppb.errors import BadEventHandlerException
+from ppb.utils import camel_to_snake
 
 @mark.parametrize("text,expected", [
     ("CamelCase", "camel_case"),

tests/test_testutil.py

@@ -9,12 +9,12 @@
 from ppb.events import Quit
 
 
-@mark.parametrize("loop_count", range(1, 6))
+@mark.parametrize("loop_count", list(range(1, 6)))
 def test_quitter(loop_count):
     quitter = testutil.Quitter(loop_count=loop_count)
     signal_mock = Mock()
     for i in range(loop_count):
-        quitter.__event__(Idle(.01), signal_mock)
+        quitter.on_idle(Idle(.01), signal_mock)
     signal_mock.assert_called_once()
     assert len(signal_mock.call_args[0]) == 1
     assert len(signal_mock.call_args[1]) == 0
@@ -25,7 +25,7 @@ def test_failer_immediate():
     failer = testutil.Failer(fail=lambda e: True, message="Expected failure.", engine=None)
 
     with raises(AssertionError):
-        failer.__event__(Idle(0.0), lambda x: None)
+        failer.on_idle(Idle(0.0), lambda x: None)
 
 
 def test_failer_timed():
@@ -35,7 +35,7 @@ def test_failer_timed():
 
     while True:
         try:
-            failer.__event__(Idle(0.0), lambda x: None)
+            failer.on_idle(Idle(0.0), lambda x: None)
         except AssertionError as e:
             if e.args[0] == "Test ran too long.":
                 end_time = monotonic()