From a823dd243e2bb9d8eaded78f102e985be1ae4722 Mon Sep 17 00:00:00 2001
From: wakonig_k <klaus.wakonig@psi.ch>
Date: Fri, 29 Aug 2025 15:39:58 +0200
Subject: [PATCH] feat: add SafeConnect

---
 bec_widgets/utils/bec_widget.py   |  9 +++---
 bec_widgets/utils/error_popups.py | 48 +++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+), 5 deletions(-)

diff --git a/bec_widgets/utils/bec_widget.py b/bec_widgets/utils/bec_widget.py
index 67a4c5e9..34a80ee2 100644
--- a/bec_widgets/utils/bec_widget.py
+++ b/bec_widgets/utils/bec_widget.py
@@ -11,7 +11,7 @@ from qtpy.QtWidgets import QApplication, QFileDialog, QWidget
 
 from bec_widgets.cli.rpc.rpc_register import RPCRegister
 from bec_widgets.utils.bec_connector import BECConnector, ConnectionConfig
-from bec_widgets.utils.error_popups import SafeSlot
+from bec_widgets.utils.error_popups import SafeConnect, SafeSlot
 from bec_widgets.utils.rpc_decorator import rpc_timeout
 from bec_widgets.utils.widget_io import WidgetHierarchy
 
@@ -61,7 +61,6 @@ class BECWidget(BECConnector):
         )
         if not isinstance(self, QObject):
             raise RuntimeError(f"{repr(self)} is not a subclass of QWidget")
-
         if theme_update:
             logger.debug(f"Subscribing to theme updates for {self.__class__.__name__}")
             self._connect_to_theme_change()
@@ -70,10 +69,10 @@ class BECWidget(BECConnector):
         """Connect to the theme change signal."""
         qapp = QApplication.instance()
         if hasattr(qapp, "theme"):
-            qapp.theme.theme_changed.connect(self._update_theme)
+            SafeConnect(self, qapp.theme.theme_changed, self._update_theme)
 
-    @SafeSlot(str, verify_sender=True)
-    @SafeSlot(verify_sender=True)
+    @SafeSlot(str)
+    @SafeSlot()
     def _update_theme(self, theme: str | None = None):
         """Update the theme."""
         if theme is None:
diff --git a/bec_widgets/utils/error_popups.py b/bec_widgets/utils/error_popups.py
index d2ead3dd..730fcdce 100644
--- a/bec_widgets/utils/error_popups.py
+++ b/bec_widgets/utils/error_popups.py
@@ -2,7 +2,9 @@ import functools
 import sys
 import traceback
 
+import shiboken6
 from bec_lib.logger import bec_logger
+from louie.saferef import safe_ref
 from qtpy.QtCore import Property, QObject, Qt, Signal, Slot
 from qtpy.QtWidgets import QApplication, QMessageBox, QPushButton, QVBoxLayout, QWidget
 
@@ -90,6 +92,52 @@ def SafeProperty(prop_type, *prop_args, popup_error: bool = False, default=None,
     return decorator
 
 
+def _safe_connect_slot(weak_instance, weak_slot, *connect_args):
+    """Internal function used by SafeConnect to handle weak references to slots."""
+    instance = weak_instance()
+    slot_func = weak_slot()
+
+    # Check if the python object has already been garbage collected
+    if instance is None or slot_func is None:
+        return
+
+    # Check if the python object has already been marked for deletion
+    if getattr(instance, "_destroyed", False):
+        return
+
+    # Check if the C++ object is still valid
+    if not shiboken6.isValid(instance):
+        return
+
+    if connect_args:
+        slot_func(*connect_args)
+    slot_func()
+
+
+def SafeConnect(instance, signal, slot):  # pylint: disable=invalid-name
+    """
+    Method to safely handle Qt signal-slot connections. The python object is only forwarded
+    as a weak reference to avoid stale objects.
+
+    Args:
+        instance: The instance to connect.
+        signal: The signal to connect to.
+        slot: The slot to connect.
+
+    Example:
+        >>> SafeConnect(self, qapp.theme.theme_changed, self._update_theme)
+
+    """
+    weak_instance = safe_ref(instance)
+    weak_slot = safe_ref(slot)
+
+    # Create a partial function that will check weak references before calling the actual slot
+    safe_slot = functools.partial(_safe_connect_slot, weak_instance, weak_slot)
+
+    # Connect the signal to the safe connect slot wrapper
+    return signal.connect(safe_slot)
+
+
 def SafeSlot(*slot_args, **slot_kwargs):  # pylint: disable=invalid-name
     """Function with args, acting like a decorator, applying "error_managed" decorator + Qt Slot
     to the passed function, to display errors instead of potentially raising an exception