feat: context manager protocol

This makes it easy to disconnect the bus once you are done.

Author: xi

README.md

@@ -82,31 +82,31 @@ import asyncio
 
 
 async def main():
-    bus = await MessageBus().connect()
-    # the introspection xml would normally be included in your project, but
-    # this is convenient for development
-    introspection = await bus.introspect('org.mpris.MediaPlayer2.vlc', '/org/mpris/MediaPlayer2')
+    async with MessageBus() as bus:
+        # the introspection xml would normally be included in your project, but
+        # this is convenient for development
+        introspection = await bus.introspect('org.mpris.MediaPlayer2.vlc', '/org/mpris/MediaPlayer2')
 
-    obj = bus.get_proxy_object('org.mpris.MediaPlayer2.vlc', '/org/mpris/MediaPlayer2', introspection)
-    player = obj.get_interface('org.mpris.MediaPlayer2.Player')
-    properties = obj.get_interface('org.freedesktop.DBus.Properties')
+        obj = bus.get_proxy_object('org.mpris.MediaPlayer2.vlc', '/org/mpris/MediaPlayer2', introspection)
+        player = obj.get_interface('org.mpris.MediaPlayer2.Player')
+        properties = obj.get_interface('org.freedesktop.DBus.Properties')
 
-    # call methods on the interface (this causes the media player to play)
-    await player.call_play()
+        # call methods on the interface (this causes the media player to play)
+        await player.call_play()
 
-    volume = await player.get_volume()
-    print(f'current volume: {volume}, setting to 0.5')
+        volume = await player.get_volume()
+        print(f'current volume: {volume}, setting to 0.5')
 
-    await player.set_volume(0.5)
+        await player.set_volume(0.5)
 
-    # listen to signals
-    def on_properties_changed(interface_name, changed_properties, invalidated_properties):
-        for changed, variant in changed_properties.items():
-            print(f'property changed: {changed} - {variant.value}')
+        # listen to signals
+        def on_properties_changed(interface_name, changed_properties, invalidated_properties):
+            for changed, variant in changed_properties.items():
+                print(f'property changed: {changed} - {variant.value}')
 
-    properties.on_properties_changed(on_properties_changed)
+        properties.on_properties_changed(on_properties_changed)
 
-    await asyncio.Event().wait()
+        await asyncio.Event().wait()
 
 asyncio.run(main())
 ```
@@ -155,13 +155,13 @@ class ExampleInterface(ServiceInterface):
         return 'hello'
 
 async def main():
-    bus = await MessageBus().connect()
-    interface = ExampleInterface('test.interface')
-    bus.export('/test/path', interface)
-    # now that we are ready to handle requests, we can request name from D-Bus
-    await bus.request_name('test.name')
-    # wait indefinitely
-    await asyncio.Event().wait()
+    async with MessageBus() as bus:
+        interface = ExampleInterface('test.interface')
+        bus.export('/test/path', interface)
+        # now that we are ready to handle requests, we can request name from D-Bus
+        await bus.request_name('test.name')
+        # wait indefinitely
+        await asyncio.Event().wait()
 
 asyncio.run(main())
 ```
@@ -181,13 +181,12 @@ import json
 
 
 async def main():
-    bus = await MessageBus().connect()
-
-    reply = await bus.call(
-        Message(destination='org.freedesktop.DBus',
-                path='/org/freedesktop/DBus',
-                interface='org.freedesktop.DBus',
-                member='ListNames'))
+    async with MessageBus() as bus:
+        reply = await bus.call(
+            Message(destination='org.freedesktop.DBus',
+                    path='/org/freedesktop/DBus',
+                    interface='org.freedesktop.DBus',
+                    member='ListNames'))
 
     if reply.message_type == MessageType.ERROR:
         raise Exception(reply.body[0])

src/dbus_fast/aio/message_bus.py

@@ -219,6 +219,12 @@ def __init__(
         self._disconnect_future = self._loop.create_future()
         self._pending_futures: set[asyncio.Future] = set()
 
+    async def __aenter__(self) -> MessageBus:
+        return await self.connect()
+
+    async def __aexit__(self, *args, **kwargs) -> None:
+        self.disconnect()
+
     async def connect(self) -> MessageBus:
         """Connect this message bus to the DBus daemon.
 

src/dbus_fast/glib/message_bus.py

@@ -178,6 +178,12 @@ def __init__(
         else:
             self._auth = auth
 
+    def __enter__(self) -> "MessageBus":
+        return self.connect_sync()
+
+    def __exit__(self, *args, **kwargs) -> None:
+        self.disconnect()
+
     def _on_message(self, msg: Message) -> None:
         try:
             self._process_message(msg)

tests/test_disconnect.py

@@ -74,3 +74,14 @@ def send(self, *args, **kwargs):
     bus.disconnect()
     with pytest.raises(OSError):
         await asyncio.wait_for(bus.wait_for_disconnect(), timeout=1)
+
+
+@pytest.mark.asyncio
+async def test_context_manager():
+    bus = MessageBus()
+
+    assert not bus.connected
+    async with bus:
+        assert bus.connected
+
+    assert not bus.connected

tests/test_glib_low_level.py

@@ -178,3 +178,14 @@ def message_handler(signal):
 
     bus1.disconnect()
     bus2.disconnect()
+
+
+@pytest.mark.skipif(not has_gi, reason=skip_reason_no_gi)
+def test_context_manager():
+    bus = MessageBus()
+
+    assert not bus.connected
+    with bus:
+        assert bus.connected
+
+    assert not bus.connected