Use __init_subclass__ instead of metaclass

it's a bit simpler and doesn't confuse type checkers as much

ai_diffusion/connection.py

@@ -7,7 +7,7 @@
 from .client import Client, ClientMessage, ClientEvent, DeviceInfo, MissingResource
 from .network import NetworkError
 from .settings import Settings, PerformancePreset, settings
-from .properties import Property, PropertyMeta
+from .properties import Property, ObservableProperties
 from . import util, eventloop
 
 
@@ -18,7 +18,7 @@ class ConnectionState(Enum):
     error = 3
 
 
-class Connection(QObject, metaclass=PropertyMeta):
+class Connection(QObject, ObservableProperties):
     state = Property(ConnectionState.disconnected)
     error = Property("")
     missing_resource: MissingResource | None = None

ai_diffusion/control.py

@@ -5,12 +5,12 @@
 from .settings import settings
 from .resources import ControlMode
 from .client import resolve_sd_version
-from .properties import Property, PropertyMeta
+from .properties import Property, ObservableProperties
 from .image import Bounds
 from .workflow import Control
 
 
-class ControlLayer(QObject, metaclass=PropertyMeta):
+class ControlLayer(QObject, ObservableProperties):
     mode = Property(ControlMode.image, persist=True)
     layer_id = Property(QUuid(), persist=True)
     strength = Property(100, persist=True)

ai_diffusion/model.py

@@ -1,21 +1,20 @@
 from __future__ import annotations
-import asyncio
 import random
 from enum import Enum
-from typing import NamedTuple, cast
+from typing import NamedTuple
 from PyQt5.QtCore import QObject, pyqtSignal
 
 from . import eventloop, workflow, util
 from .settings import settings
 from .network import NetworkError
-from .image import Extent, Image, ImageCollection, Mask, Bounds
+from .image import Extent, Image, Mask, Bounds
 from .client import ClientMessage, ClientEvent, filter_supported_styles, resolve_sd_version
 from .document import Document, LayerObserver
 from .pose import Pose
 from .style import Style, Styles, SDVersion
 from .workflow import ControlMode, Conditioning, LiveParams
-from .connection import Connection, ConnectionState
-from .properties import Property, PropertyMeta
+from .connection import Connection
+from .properties import Property, ObservableProperties
 from .jobs import Job, JobKind, JobQueue, JobState
 from .control import ControlLayer, ControlLayerList
 import krita
@@ -27,7 +26,7 @@ class Workspace(Enum):
     live = 2
 
 
-class Model(QObject, metaclass=PropertyMeta):
+class Model(QObject, ObservableProperties):
     """Represents diffusion workflows for a specific Krita document. Stores all inputs related to
     image generation. Launches generation jobs. Listens to server messages and keeps a
     list of finished, currently running and enqueued jobs.
@@ -364,7 +363,7 @@ class UpscaleParams(NamedTuple):
     target_extent: Extent
 
 
-class UpscaleWorkspace(QObject, metaclass=PropertyMeta):
+class UpscaleWorkspace(QObject, ObservableProperties):
     upscaler = Property("", persist=True)
     factor = Property(2.0, persist=True)
     use_diffusion = Property(True, persist=True)
@@ -401,7 +400,7 @@ def params(self):
         )
 
 
-class LiveWorkspace(QObject, metaclass=PropertyMeta):
+class LiveWorkspace(QObject, ObservableProperties):
     is_active = Property(False, setter="toggle")
     strength = Property(0.3, persist=True)
     seed = Property(0, persist=True)

ai_diffusion/properties.py

@@ -1,31 +1,30 @@
 from enum import Enum
 from typing import Any, NamedTuple, Sequence, TypeVar, Generic
 
-from PyQt5.QtCore import QObject, QMetaObject, QUuid, pyqtBoundSignal, pyqtProperty  # type: ignore
+from PyQt5.QtCore import QObject, QMetaObject, QUuid, pyqtBoundSignal
 from PyQt5.QtWidgets import QComboBox
 
 
 T = TypeVar("T")
 
 
-class PropertyMeta(type(QObject)):
-    """Provides default implementations for properties (get, set, signal)."""
+class ObservableProperties:
+    """Provides default implementations for properties (get, set, signal) to sub-classes."""
 
-    def __new__(cls, name, bases, attrs):
-        for key in list(attrs.keys()):
-            attr = attrs[key]
-            if not isinstance(attr, Property):
-                continue
+    def __init_subclass__(cls, **kwargs):
+        super().__init_subclass__(**kwargs)
 
-            attrs[f"_{key}"] = attr.default_value
+        properties = {
+            name: attr for name, attr in cls.__dict__.items() if isinstance(attr, Property)
+        }
+        for name, property in properties.items():
+            setattr(cls, f"_{name}", property.default_value)
             getter, setter = None, None
-            if attr.getter is not None:
-                getter = attrs[attr.getter]
-            if attr.setter is not None:
-                setter = attrs[attr.setter]
-            attrs[key] = PropertyImpl(key, getter, setter, attr.persist)
-
-        return super().__new__(cls, name, bases, attrs)
+            if property.getter is not None:
+                getter = getattr(cls, property.getter)
+            if property.setter is not None:
+                setter = getattr(cls, property.setter)
+            setattr(cls, name, PropertyImpl(name, getter, setter, property.persist))
 
 
 class Property(Generic[T]):
@@ -48,7 +47,7 @@ def __delete__(self, instance): ...
 
 
 class PropertyImpl(property):
-    """Property implementation: gets, sets, and notifies of change."""
+    """Property implementation: gets/sets a value, and emits a signal when it changes."""
 
     name: str
     persist: bool

tests/test_properties.py

@@ -1,16 +1,16 @@
 from enum import Enum
 import pytest
-from PyQt5.QtCore import QObject, pyqtBoundSignal, pyqtSignal
+from PyQt5.QtCore import QObject, pyqtSignal
 
-from ai_diffusion.properties import Property, PropertyMeta, bind, serialize, deserialize
+from ai_diffusion.properties import Property, ObservableProperties, bind, serialize, deserialize
 
 
 class Piong(Enum):
     a = 1
     b = 2
 
 
-class ObjectWithProperties(QObject, metaclass=PropertyMeta):
+class ObjectWithProperties(QObject, ObservableProperties):
     inty = Property(0)
     stringy = Property("")
     enumy = Property(Piong.a)
@@ -73,6 +73,15 @@ def callback(x):
     assert called == [42, "hello", Piong.b, 5, 55]
 
 
+def test_multiple():
+    a = ObjectWithProperties()
+    b = ObjectWithProperties()
+
+    a.inty = 5
+    b.inty = 99
+    assert a.inty != b.inty
+
+
 def test_bind():
     a = ObjectWithProperties()
     b = ObjectWithProperties()
@@ -112,7 +121,7 @@ def test_bind_qt_to_property():
     assert a.qtstyle() == 99
 
 
-class PersistentObject(QObject, metaclass=PropertyMeta):
+class PersistentObject(QObject, ObservableProperties):
     inty = Property(0, persist=True)
     stringy = Property("", persist=True)
     enumy = Property(Piong.a, persist=True)

tests/test_workflow.py

@@ -403,7 +403,8 @@ def test_create_control_image(qtapp, comfy, mode):
     async def main():
         result = await run_and_save(comfy, job, image_name)
         reference = Image.load(reference_dir / image_name)
-        assert Image.compare(result, reference) < 0.002
+        threshold = 0.005 if mode is ControlMode.pose else 0.002
+        assert Image.compare(result, reference) < threshold
 
     qtapp.run(main())