GH-603 Permit selecting abstract types for variable definitions

src/editor/inspector/property_type_button_property.cpp

@@ -93,6 +93,7 @@ void OrchestratorEditorPropertyVariableClassification::_notification(int p_what)
         _dialog->set_popup_title("Select variable type");
         _dialog->set_data_suffix("variable_type");
         _dialog->set_base_type(_base_type);
+        _dialog->set_allow_abstract_types(true);
         add_child(_dialog);
 
         _dialog->connect("selected", callable_mp(this, &OrchestratorEditorPropertyVariableClassification::_search_selected));

src/editor/select_type_dialog.cpp

@@ -261,15 +261,23 @@ Vector<Ref<OrchestratorEditorSearchDialog::SearchItem>> OrchestratorSelectTypeSe
         item->icon = SceneUtils::get_class_icon(clazz_name);
         item->parent = parent;
 
-        if (!ClassDB::can_instantiate(clazz_name))
+        if (!_allow_abstract_types)
         {
-            item->selectable = false;
-            item->disabled = true;
+            if (!ClassDB::can_instantiate(clazz_name))
+            {
+                item->selectable = false;
+                item->disabled = true;
+            }
+            else if (Engine::get_singleton()->get_singleton_list().has(clazz_name))
+            {
+                item->selectable = false;
+                item->disabled = true;
+            }
         }
-        else if (Engine::get_singleton()->get_singleton_list().has(clazz_name))
+        else
         {
-            item->selectable = false;
-            item->disabled = true;
+            item->selectable = true;
+            item->disabled = false;
         }
 
         if (ScriptServer::is_global_class(clazz_name))

src/editor/select_type_dialog.h

@@ -45,6 +45,7 @@ class OrchestratorSelectTypeSearchDialog : public OrchestratorEditorSearchDialog
     HashSet<StringName> _exclusions;                  //! Set of types to be excluded
     Vector<String> _variant_type_names;               //! All valid variant type names
     bool _is_base_type_node{ false };                 //! Specifies if base type is a Node
+    bool _allow_abstract_types{ false };              //! Allow selecting abstract types
     String _base_type;                                //! The base type
     String _fallback_icon{ "Object" };                //! The fallback icon
     String _preferred_search_result_type;             //! The preferred search result type
@@ -101,6 +102,10 @@ class OrchestratorSelectTypeSearchDialog : public OrchestratorEditorSearchDialog
     /// @param p_data_suffix the data file suffix
     void set_data_suffix(const String& p_data_suffix) { _data_suffix = p_data_suffix; }
 
+    /// Sets whether abstract types should be selectable
+    /// @param p_allow_abstract_types true to allow selecting abstract types
+    void set_allow_abstract_types(bool p_allow_abstract_types) { _allow_abstract_types = p_allow_abstract_types; }
+
     /// Sets the dialog's title
     /// @param p_title the title to be used
     void set_popup_title(const String& p_title) { _title = p_title; }