From 2c39f2274a916feaf9b49f95538ad21e2b520e64 Mon Sep 17 00:00:00 2001
From: Ivan Kosarev <ivan@kosarev.info>
Date: Fri, 19 Feb 2021 22:13:47 +0200
Subject: [PATCH] [#18] Introduce dispatchers.

---
 zx/_emulator.py | 13 ++++++-------
 zx/_machine.py  | 21 ++++++++++++++++-----
 2 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/zx/_emulator.py b/zx/_emulator.py
index 4e75bae..a93e365 100644
--- a/zx/_emulator.py
+++ b/zx/_emulator.py
@@ -22,6 +22,7 @@
 from ._gui import ScreenWindow
 from ._keyboard import KeyboardState
 from ._keyboard import KEYS
+from ._machine import Dispatcher
 from ._machine import RunEvents
 from ._machine import Spectrum48
 from ._rzx import RZXFile
@@ -63,12 +64,10 @@ def __init__(self, speed_factor=1.0, profile=None, devices=None):
         self.__events_to_signal = RunEvents.NO_EVENTS
 
         # Don't even create the window on full throttle.
-        self.__devices = devices if devices is not None else []
         if devices is None and self.__speed_factor is not None:
-            self.__devices = [ScreenWindow(self)]
+            devices = Dispatcher([ScreenWindow(self)])
 
-        # TODO: Eliminate the undescored version.
-        self.devices = self.__devices
+        self.devices = devices
 
         self.__keyboard_state = KeyboardState()
         self.set_on_input_callback(self.__on_input)
@@ -100,7 +99,7 @@ def _is_tape_paused(self):
 
     def __pause_tape(self, is_paused=True):
         self._tape_player.pause(is_paused)
-        self.notify_devices(TapeStateUpdated())
+        self.devices.notify(TapeStateUpdated())
 
     def __unpause_tape(self):
         self.__pause_tape(is_paused=False)
@@ -278,7 +277,7 @@ def __run_quantum(self, speed_factor=None):
             creator_info = self.__playback_player.find_recording_info_chunk()
 
         if True:  # TODO
-            self.notify_devices(QuantumRun())
+            self.devices.notify(QuantumRun())
 
             # TODO: For debug purposes.
             '''
@@ -323,7 +322,7 @@ def __run_quantum(self, speed_factor=None):
                 self.render_screen()
 
                 pixels = self.get_frame_pixels()
-                self.notify_devices(ScreenUpdated(pixels))
+                self.devices.notify(ScreenUpdated(pixels))
 
                 self._tape_player.skip_rest_of_frame()
                 self._emulation_time.advance(1 / 50)
diff --git a/zx/_machine.py b/zx/_machine.py
index df6c371..be241fc 100644
--- a/zx/_machine.py
+++ b/zx/_machine.py
@@ -342,6 +342,21 @@ def install_snapshot(self, snapshot):
                 setattr(self, field, value)
 
 
+class Dispatcher(object):
+    def __init__(self, devices=None):
+        if devices is None:
+            devices = []
+
+        self.__devices = list(devices)
+
+    def __iter__(self):
+        yield from self.__devices
+
+    def notify(self, event):
+        for device in self:
+            device.on_event(event)
+
+
 class Spectrum48(_Spectrum48Base, MachineState):
     # Memory marks.
     __NO_MARKS = 0
@@ -369,10 +384,6 @@ def __exit__(self, type, value, tb):
     def stop(self):
         raise EmulationExit()
 
-    def notify_devices(self, event):
-        for device in self.devices:
-            device.on_event(event)
-
     @property
     def paused(self):
         return self.__paused
@@ -380,7 +391,7 @@ def paused(self):
     @paused.setter
     def paused(self, value):
         self.__paused = value
-        self.notify_devices(PauseStateUpdated())
+        self.devices.notify(PauseStateUpdated())
 
     def set_breakpoints(self, addr, size):
         self.mark_addrs(addr, size, self.__BREAKPOINT_MARK)