fix: fix callback of throttled/debounced decorated functions with mismatched args (#184)

* fix: fix throttled inspection

* build: change typing-ext deps

* fix: use inspect.signature

* use get_max_args

* fix: fix typing

.github/workflows/test_and_deploy.yml

@@ -100,7 +100,7 @@ jobs:
         run: |
           python -m pip install -U pip
           python -m pip install -e .[test,pyqt5]
-          python -m pip install qtpy==1.1.0 typing-extensions==3.10.0.0
+          python -m pip install qtpy==1.1.0 typing-extensions==3.7.4.3
 
       - name: Test
         uses: aganders3/headless-gui@v1.2

pyproject.toml

@@ -41,7 +41,7 @@ dependencies = [
     "packaging",
     "pygments>=2.4.0",
     "qtpy>=1.1.0",
-    "typing-extensions",
+    "typing-extensions >=3.7.4.3,!=3.10.0.0",
 ]
 
 # extras

src/superqt/utils/_throttler.py

@@ -26,17 +26,19 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 
 """
-import sys
+from __future__ import annotations
+
 from concurrent.futures import Future
 from enum import IntFlag, auto
 from functools import wraps
-from typing import TYPE_CHECKING, Callable, Generic, Optional, TypeVar, Union, overload
+from typing import TYPE_CHECKING, Callable, Generic, TypeVar, overload
 
 from qtpy.QtCore import QObject, Qt, QTimer, Signal
 
+from ._util import get_max_args
+
 if TYPE_CHECKING:
-    from qtpy.QtCore import SignalInstance
+    from typing_extensions import ParamSpec
-    from typing_extensions import Literal, ParamSpec
 
     P = ParamSpec("P")
 # maintain runtime compatibility with older typing_extensions
@@ -70,7 +72,7 @@ class GenericSignalThrottler(QObject):
         self,
         kind: Kind,
         emissionPolicy: EmissionPolicy,
-        parent: Optional[QObject] = None,
+        parent: QObject | None = None,
     ) -> None:
         super().__init__(parent)
 
@@ -166,7 +168,7 @@ class QSignalThrottler(GenericSignalThrottler):
     def __init__(
         self,
         policy: EmissionPolicy = EmissionPolicy.Leading,
-        parent: Optional[QObject] = None,
+        parent: QObject | None = None,
     ) -> None:
         super().__init__(Kind.Throttler, policy, parent)
 
@@ -181,7 +183,7 @@ class QSignalDebouncer(GenericSignalThrottler):
     def __init__(
         self,
         policy: EmissionPolicy = EmissionPolicy.Trailing,
-        parent: Optional[QObject] = None,
+        parent: QObject | None = None,
     ) -> None:
         super().__init__(Kind.Debouncer, policy, parent)
 
@@ -189,30 +191,44 @@ class QSignalDebouncer(GenericSignalThrottler):
 # below here part is unique to superqt (not from KD)
 
 
-if TYPE_CHECKING:
+class ThrottledCallable(GenericSignalThrottler, Generic[P, R]):
-    from typing_extensions import Protocol
+    def __init__(
+        self,
+        func: Callable[P, R],
+        kind: Kind,
+        emissionPolicy: EmissionPolicy,
+        parent: QObject | None = None,
+    ) -> None:
+        super().__init__(kind, emissionPolicy, parent)
 
-    class ThrottledCallable(Generic[P, R], Protocol):
+        self._future: Future[R] = Future()
-        triggered: "SignalInstance"
+        self.__wrapped__ = func
 
-        def cancel(self) -> None:
+        self._args: tuple = ()
-            ...
+        self._kwargs: dict = {}
+        self.triggered.connect(self._set_future_result)
 
-        def flush(self) -> None:
+        # even if we were to compile __call__ with a signature matching that of func,
-            ...
+        # PySide wouldn't correctly inspect the signature of the ThrottledCallable
+        # instance: https://bugreports.qt.io/browse/PYSIDE-2423
+        # so we do it ourselfs and limit the number of positional arguments
+        # that we pass to func
+        self._max_args: int | None = get_max_args(func)
 
-        def set_timeout(self, timeout: int) -> None:
+    def __call__(self, *args: P.args, **kwargs: P.kwargs) -> "Future[R]":  # noqa
-            ...
+        if not self._future.done():
+            self._future.cancel()
 
-        if sys.version_info < (3, 9):
+        self._future = Future()
+        self._args = args
+        self._kwargs = kwargs
 
-            def __call__(self, *args: "P.args", **kwargs: "P.kwargs") -> Future:
+        self.throttle()
-                ...
+        return self._future
 
-        else:
+    def _set_future_result(self):
-
+        result = self.__wrapped__(*self._args[: self._max_args], **self._kwargs)
-            def __call__(self, *args: "P.args", **kwargs: "P.kwargs") -> Future[R]:
+        self._future.set_result(result)
-                ...
 
 
 @overload
@@ -221,28 +237,26 @@ def qthrottled(
     timeout: int = 100,
     leading: bool = True,
     timer_type: Qt.TimerType = Qt.TimerType.PreciseTimer,
-) -> "ThrottledCallable[P, R]":
+) -> ThrottledCallable[P, R]:
     ...
 
 
 @overload
 def qthrottled(
-    func: Optional["Literal[None]"] = None,
+    func: None = ...,
     timeout: int = 100,
     leading: bool = True,
     timer_type: Qt.TimerType = Qt.TimerType.PreciseTimer,
-) -> Callable[[Callable[P, R]], "ThrottledCallable[P, R]"]:
+) -> Callable[[Callable[P, R]], ThrottledCallable[P, R]]:
     ...
 
 
 def qthrottled(
-    func: Optional[Callable[P, R]] = None,
+    func: Callable[P, R] | None = None,
     timeout: int = 100,
     leading: bool = True,
     timer_type: Qt.TimerType = Qt.TimerType.PreciseTimer,
-) -> Union[
+) -> ThrottledCallable[P, R] | Callable[[Callable[P, R]], ThrottledCallable[P, R]]:
-    "ThrottledCallable[P, R]", Callable[[Callable[P, R]], "ThrottledCallable[P, R]"]
-]:
     """Creates a throttled function that invokes func at most once per timeout.
 
     The throttled function comes with a `cancel` method to cancel delayed func
@@ -280,28 +294,26 @@ def qdebounced(
     timeout: int = 100,
     leading: bool = False,
     timer_type: Qt.TimerType = Qt.TimerType.PreciseTimer,
-) -> "ThrottledCallable[P, R]":
+) -> ThrottledCallable[P, R]:
     ...
 
 
 @overload
 def qdebounced(
-    func: Optional["Literal[None]"] = None,
+    func: None = ...,
     timeout: int = 100,
     leading: bool = False,
     timer_type: Qt.TimerType = Qt.TimerType.PreciseTimer,
-) -> Callable[[Callable[P, R]], "ThrottledCallable[P, R]"]:
+) -> Callable[[Callable[P, R]], ThrottledCallable[P, R]]:
     ...
 
 
 def qdebounced(
-    func: Optional[Callable[P, R]] = None,
+    func: Callable[P, R] | None = None,
     timeout: int = 100,
     leading: bool = False,
     timer_type: Qt.TimerType = Qt.TimerType.PreciseTimer,
-) -> Union[
+) -> ThrottledCallable[P, R] | Callable[[Callable[P, R]], ThrottledCallable[P, R]]:
-    "ThrottledCallable[P, R]", Callable[[Callable[P, R]], "ThrottledCallable[P, R]"]
-]:
     """Creates a debounced function that delays invoking `func`.
 
     `func` will not be invoked until `timeout` ms have elapsed since the last time
@@ -337,41 +349,17 @@ def qdebounced(
 
 
 def _make_decorator(
-    func: Optional[Callable[P, R]],
+    func: Callable[P, R] | None,
     timeout: int,
     leading: bool,
     timer_type: Qt.TimerType,
     kind: Kind,
-) -> Union[
+) -> ThrottledCallable[P, R] | Callable[[Callable[P, R]], ThrottledCallable[P, R]]:
-    "ThrottledCallable[P, R]", Callable[[Callable[P, R]], "ThrottledCallable[P, R]"]
+    def deco(func: Callable[P, R]) -> ThrottledCallable[P, R]:
-]:
-    def deco(func: Callable[P, R]) -> "ThrottledCallable[P, R]":
         policy = EmissionPolicy.Leading if leading else EmissionPolicy.Trailing
-        throttle = GenericSignalThrottler(kind, policy)
+        obj = ThrottledCallable(func, kind, policy)
-        throttle.setTimerType(timer_type)
+        obj.setTimerType(timer_type)
-        throttle.setTimeout(timeout)
+        obj.setTimeout(timeout)
-        last_f = None
+        return wraps(func)(obj)
-        future: Optional[Future] = None
-
-        @wraps(func)
-        def inner(*args: "P.args", **kwargs: "P.kwargs") -> Future:
-            nonlocal last_f
-            nonlocal future
-            if last_f is not None:
-                throttle.triggered.disconnect(last_f)
-            if future is not None and not future.done():
-                future.cancel()
-
-            future = Future()
-            last_f = lambda: future.set_result(func(*args, **kwargs))  # noqa
-            throttle.triggered.connect(last_f)
-            throttle.throttle()
-            return future
-
-        inner.cancel = throttle.cancel
-        inner.flush = throttle.flush
-        inner.set_timeout = throttle.setTimeout
-        inner.triggered = throttle.triggered
-        return inner  # type: ignore
 
     return deco(func) if func is not None else deco

tests/test_throttler.py

@@ -1,5 +1,8 @@
 from unittest.mock import Mock
 
+import pytest
+from qtpy.QtCore import QObject, Signal
+
 from superqt.utils import qdebounced, qthrottled
 
 
@@ -41,3 +44,29 @@ def test_throttled(qtbot):
     qtbot.wait(5)
     assert mock1.call_count == 2
     assert mock2.call_count == 10
+
+
+@pytest.mark.parametrize("deco", [qthrottled, qdebounced])
+def test_ensure_throttled_sig_inspection(deco, qtbot):
+    mock = Mock()
+
+    class Emitter(QObject):
+        sig = Signal(int, int, int)
+
+    @deco
+    def func(a: int, b: int):
+        """docstring"""
+        mock(a, b)
+
+    obj = Emitter()
+    obj.sig.connect(func)
+
+    # this is the crux of the test...
+    # we emit 3 args, but the function only takes 2
+    # this should normally work fine in Qt.
+    # testing here that the decorator doesn't break it.
+    with qtbot.waitSignal(func.triggered, timeout=1000):
+        obj.sig.emit(1, 2, 3)
+    mock.assert_called_once_with(1, 2)
+    assert func.__doc__ == "docstring"
+    assert func.__name__ == "func"