Fix errors on Variable Explorer and Debugger when current widget is e…

…mpty

Also, introduce a new method to ShellConnectMainWidget to easily
check if the current widget is an empty one.

spyder/api/shellconnect/main_widget.py

@@ -43,6 +43,24 @@ def __init__(self, *args, **kwargs):
         layout.addWidget(self._stack)
         self.setLayout(layout)
 
+    # ---- PluginMainWidget API
+    # ------------------------------------------------------------------------
+    def current_widget(self):
+        """
+        Return the current figure browser widget in the stack.
+
+        Returns
+        -------
+        QWidget
+            The current widget.
+        """
+        return self._stack.currentWidget()
+
+    def get_focus_widget(self):
+        return self.current_widget()
+
+    # ---- SpyderWidgetMixin API
+    # ------------------------------------------------------------------------
     def update_style(self):
         self._stack.setStyleSheet("QStackedWidget {padding: 0px; border: 0px}")
 
@@ -59,20 +77,6 @@ def count(self):
         """
         return self._stack.count()
 
-    def current_widget(self):
-        """
-        Return the current figure browser widget in the stack.
-
-        Returns
-        -------
-        QWidget
-            The current widget.
-        """
-        return self._stack.currentWidget()
-
-    def get_focus_widget(self):
-        return self.current_widget()
-
     def get_widget_for_shellwidget(self, shellwidget):
         """return widget corresponding to shellwidget."""
         shellwidget_id = id(shellwidget)
@@ -163,3 +167,7 @@ def refresh(self):
         if self.count():
             widget = self.current_widget()
             widget.refresh()
+
+    def is_current_widget_empty(self):
+        """Check if the current widget is a PaneEmptyWidget."""
+        return isinstance(self.current_widget(), PaneEmptyWidget)

spyder/plugins/debugger/widgets/main_widget.py

@@ -341,6 +341,9 @@ def setup(self):
     def update_actions(self):
         """Update actions."""
         widget = self.current_widget()
+        if self.is_current_widget_empty():
+            return
+
         search_action = self.get_action(DebuggerWidgetActions.Search)
         enter_debug_action = self.get_action(
             DebuggerWidgetActions.EnterDebug)
@@ -361,6 +364,7 @@ def update_actions(self):
             show_enter_debugger = post_mortem or executing
             is_inspecting = widget.state == FramesBrowserState.Inspect
             pdb_prompt = sw.is_waiting_pdb_input()
+
         search_action.setChecked(search)
         enter_debug_action.setEnabled(show_enter_debugger)
         inspect_action.setEnabled(executing)
@@ -372,8 +376,7 @@ def update_actions(self):
                 DebuggerWidgetActions.Step,
                 DebuggerWidgetActions.Return,
                 DebuggerWidgetActions.Stop,
-                DebuggerWidgetActions.GotoCursor,
-                ]:
+                DebuggerWidgetActions.GotoCursor]:
             action = self.get_action(action_name)
             action.setEnabled(pdb_prompt)
 
@@ -490,22 +493,22 @@ def set_pdb_take_focus(self, take_focus):
         next call.
         """
         widget = self.current_widget()
-        if widget is None:
+        if widget is None or self.is_current_widget_empty():
             return False
         widget.shellwidget._pdb_take_focus = take_focus
 
     @Slot(bool)
     def toggle_finder(self, checked):
         """Show or hide finder."""
         widget = self.current_widget()
-        if widget is None:
+        if widget is None or self.is_current_widget_empty():
             return
         widget.toggle_finder(checked)
 
     def get_pdb_state(self):
         """Get debugging state of the current console."""
         widget = self.current_widget()
-        if widget is None or not hasattr(widget, 'shellwidget'):
+        if widget is None or self.is_current_widget_empty():
             return False
         sw = widget.shellwidget
         if sw is not None:
@@ -515,7 +518,7 @@ def get_pdb_state(self):
     def get_pdb_last_step(self):
         """Get last pdb step of the current console."""
         widget = self.current_widget()
-        if widget is None or not hasattr(widget, 'shellwidget'):
+        if widget is None or self.is_current_widget_empty():
             return None, None
         sw = widget.shellwidget
         if sw is not None:

spyder/plugins/plots/widgets/main_widget.py

@@ -216,7 +216,7 @@ def update_actions(self):
         value = False
         widget = self.current_widget()
         figviewer = None
-        if widget and hasattr(widget, 'figviewer'):
+        if widget and not self.is_current_widget_empty():
             figviewer = widget.figviewer
             thumbnails_sb = widget.thumbnails_sb
             value = figviewer.figcanvas.fig is not None

spyder/plugins/variableexplorer/widgets/main_widget.py

@@ -420,18 +420,24 @@ def setup(self):
 
     def update_actions(self):
         """Update the actions."""
+        nsb = self.current_widget()
+        if self.is_current_widget_empty():
+            return
+
         action = self.get_action(VariableExplorerWidgetActions.ToggleMinMax)
         action.setEnabled(is_module_installed('numpy'))
-        nsb = self.current_widget()
+
         if nsb:
             save_data_action = self.get_action(
                 VariableExplorerWidgetActions.SaveData)
             save_data_action.setEnabled(nsb.filename is not None)
         search_action = self.get_action(VariableExplorerWidgetActions.Search)
+
         if nsb is None:
             checked = False
         else:
             checked = nsb.finder_is_visible()
+
         search_action.setChecked(checked)
 
     @on_conf_change
@@ -483,27 +489,27 @@ def import_data(self, filenames=None):
         """
         Import data in current namespace.
         """
-        if self.count():
+        if not self.is_current_widget_empty():
             nsb = self.current_widget()
             nsb.refresh_table()
             nsb.import_data(filenames=filenames)
 
     def save_data(self):
-        if self.count():
+        if not self.is_current_widget_empty():
             nsb = self.current_widget()
             nsb.save_data()
             self.update_actions()
 
     def reset_namespace(self):
-        if self.count():
+        if not self.is_current_widget_empty():
             nsb = self.current_widget()
             nsb.reset_namespace()
 
     @Slot(bool)
     def toggle_finder(self, checked):
         """Hide or show the finder."""
         widget = self.current_widget()
-        if widget is None:
+        if widget is None or self.is_current_widget_empty():
             return
         widget.toggle_finder(checked)
 
@@ -514,7 +520,7 @@ def hide_finder(self):
         action.setChecked(False)
 
     def refresh_table(self):
-        if self.count():
+        if not self.is_current_widget_empty():
             nsb = self.current_widget()
             nsb.refresh_table()
 
@@ -530,10 +536,12 @@ def free_memory(self):
                           self.sig_free_memory_requested)
 
     def resize_rows(self):
-        self._current_editor.resizeRowsToContents()
+        if self._current_editor is not None:
+            self._current_editor.resizeRowsToContents()
 
     def resize_columns(self):
-        self._current_editor.resize_column_contents()
+        if self._current_editor is not None:
+            self._current_editor.resize_column_contents()
 
     def paste(self):
         self._current_editor.paste()
@@ -576,7 +584,7 @@ def view_item(self):
     @property
     def _current_editor(self):
         editor = None
-        if self.count():
+        if not self.is_current_widget_empty():
             nsb = self.current_widget()
             editor = nsb.editor
         return editor