Enforce passing by keyword argument in QNode and qml.execute

doc/releases/changelog-dev.md

@@ -90,6 +90,9 @@
   visualizations, allowing global and per-wire customization with options like `color`, `linestyle`, and `linewidth`.
   [(#6486)](https://github.com/PennyLaneAI/pennylane/pull/6486)
 
+* `QNode` and `qml.execute` now forbid certain keyword arguments from being passed positionally.
+  [(#6610)](https://github.com/PennyLaneAI/pennylane/pull/6610)
+
 * Shortened the string representation for the `qml.S`, `qml.T`, and `qml.SX` operators.
   [(#6542)](https://github.com/PennyLaneAI/pennylane/pull/6542)
 

pennylane/workflow/execution.py

@@ -249,6 +249,7 @@ def execute(
     device: Union["qml.devices.LegacyDevice", "qml.devices.Device"],
     diff_method: Optional[Union[Callable, str, qml.transforms.core.TransformDispatcher]] = None,
     interface: Optional[str] = "auto",
+    *,
     transform_program=None,
     inner_transform=None,
     config=None,
@@ -411,9 +412,16 @@ def cost_fn(params, x):
 
     gradient_kwargs = gradient_kwargs or {}
     mcm_config = mcm_config or {}
-    config = config or _get_execution_config(
-        diff_method, grad_on_execution, interface, device, device_vjp, mcm_config, gradient_kwargs
-    )
+    if not config:
+        config = qml.devices.ExecutionConfig(
+            interface=interface,
+            gradient_method=diff_method,
+            grad_on_execution=None if grad_on_execution == "best" else grad_on_execution,
+            use_device_jacobian_product=device_vjp,
+            mcm_config=mcm_config,
+            gradient_keyword_arguments=gradient_kwargs,
+        )
+        config = device.setup_execution_config(config)
 
     is_gradient_transform = isinstance(diff_method, qml.transforms.core.TransformDispatcher)
     transform_program, inner_transform = _make_transform_programs(
@@ -601,18 +609,3 @@ def _make_transform_programs(
             transform_program = device.preprocess_transforms(config)
 
     return transform_program, inner_transform
-
-
-def _get_execution_config(
-    diff_method, grad_on_execution, interface, device, device_vjp, mcm_config, gradient_kwargs
-):
-    """Helper function to get the execution config."""
-    config = qml.devices.ExecutionConfig(
-        interface=interface,
-        gradient_method=diff_method,
-        grad_on_execution=None if grad_on_execution == "best" else grad_on_execution,
-        use_device_jacobian_product=device_vjp,
-        mcm_config=mcm_config,
-        gradient_keyword_arguments=gradient_kwargs,
-    )
-    return device.setup_execution_config(config)

pennylane/workflow/qnode.py

@@ -607,6 +607,7 @@ def __init__(
         device: SupportedDeviceAPIs,
         interface: SupportedInterfaceUserInput = "auto",
         diff_method: Union[TransformDispatcher, SupportedDiffMethods] = "best",
+        *,
         grad_on_execution: Literal[True, False, "best"] = "best",
         cache: Union[Cache, Literal["auto", True, False]] = "auto",
         cachesize: int = 10000,