refactor: add 2 classes to refactor old code which raise too much erros by linter.

- add TinyMutex to resolve the issue that we can not operate the virtools group infos of 2 individual objects.
	* use this new class for all class need resource mutex, such as ballance element, bme materials and etc.
- add CollectionVisitor to resolve that blender have bad document and type hint for runtime bpy.types.CollectionProperty.
	* now all visit to CollectionProperty are delegated by this class.

bbp_ng/OP_ADDS_bme.py

@@ -96,27 +96,29 @@ class BBP_OT_add_bme_struct(bpy.types.Operator):
 
 
         # init data collection
+        adder_cfgs_visitor: UTIL_functions.CollectionVisitor[BBP_PG_bme_adder_cfgs]
+        adder_cfgs_visitor = UTIL_functions.CollectionVisitor(self.bme_struct_cfgs)
         # clear first
-        self.bme_struct_cfgs.clear()
+        adder_cfgs_visitor.clear()
         # create enough entries specified by gotten cfgs
         for _ in range(max(counter_int, counter_float, counter_bool)):
-            self.bme_struct_cfgs.add()
+            adder_cfgs_visitor.add()
 
         # assign default value
         for (cfg, cfg_index) in self.bme_struct_cfg_index_cache:
             # show prop differently by cfg type
             match(cfg.get_type()):
                 case UTIL_bme.PrototypeShowcaseCfgsTypes.Integer:
-                    self.bme_struct_cfgs[cfg_index].prop_int = cfg.get_default()
+                    adder_cfgs_visitor[cfg_index].prop_int = cfg.get_default()
                 case UTIL_bme.PrototypeShowcaseCfgsTypes.Float:
-                    self.bme_struct_cfgs[cfg_index].prop_float = cfg.get_default()
+                    adder_cfgs_visitor[cfg_index].prop_float = cfg.get_default()
                 case UTIL_bme.PrototypeShowcaseCfgsTypes.Boolean:
-                    self.bme_struct_cfgs[cfg_index].prop_bool = cfg.get_default()
+                    adder_cfgs_visitor[cfg_index].prop_bool = cfg.get_default()
                 case UTIL_bme.PrototypeShowcaseCfgsTypes.Face:
                     # face is just 6 bool
                     default_values: tuple[bool, ...] = cfg.get_default()
                     for i in range(6):
-                        self.bme_struct_cfgs[cfg_index + i].prop_bool = default_values[i]
+                        adder_cfgs_visitor[cfg_index + i].prop_bool = default_values[i]
 
         # reset outdated flag
         self.outdated_flag = False
@@ -182,20 +184,23 @@ class BBP_OT_add_bme_struct(bpy.types.Operator):
         # call internal updator
         self.__internal_update_bme_struct_type()
 
+        # create cfg visitor
+        adder_cfgs_visitor: UTIL_functions.CollectionVisitor[BBP_PG_bme_adder_cfgs]
+        adder_cfgs_visitor = UTIL_functions.CollectionVisitor(self.bme_struct_cfgs)
         # collect cfgs data
         cfgs: dict[str, typing.Any] = {}
         for (cfg, cfg_index) in self.bme_struct_cfg_index_cache:
             match(cfg.get_type()):
                 case UTIL_bme.PrototypeShowcaseCfgsTypes.Integer:
-                    cfgs[cfg.get_field()] = self.bme_struct_cfgs[cfg_index].prop_int
+                    cfgs[cfg.get_field()] = adder_cfgs_visitor[cfg_index].prop_int
                 case UTIL_bme.PrototypeShowcaseCfgsTypes.Float:
-                    cfgs[cfg.get_field()] = self.bme_struct_cfgs[cfg_index].prop_float
+                    cfgs[cfg.get_field()] = adder_cfgs_visitor[cfg_index].prop_float
                 case UTIL_bme.PrototypeShowcaseCfgsTypes.Boolean:
-                    cfgs[cfg.get_field()] = self.bme_struct_cfgs[cfg_index].prop_bool
+                    cfgs[cfg.get_field()] = adder_cfgs_visitor[cfg_index].prop_bool
                 case UTIL_bme.PrototypeShowcaseCfgsTypes.Face:
                     # face is just 6 bool tuple
                     cfgs[cfg.get_field()] = tuple(
-                        self.bme_struct_cfgs[cfg_index + i].prop_bool for i in range(6)
+                        adder_cfgs_visitor[cfg_index + i].prop_bool for i in range(6)
                     )
 
         # call general creator
@@ -225,6 +230,9 @@ class BBP_OT_add_bme_struct(bpy.types.Operator):
         # show type
         layout.prop(self, 'bme_struct_type')
 
+        # create cfg visitor
+        adder_cfgs_visitor: UTIL_functions.CollectionVisitor[BBP_PG_bme_adder_cfgs]
+        adder_cfgs_visitor = UTIL_functions.CollectionVisitor(self.bme_struct_cfgs)
         # visit cfgs cache list to show cfg
         layout.label(text = "Prototype Configurations:")
         for (cfg, cfg_index) in self.bme_struct_cfg_index_cache:
@@ -238,24 +246,24 @@ class BBP_OT_add_bme_struct(bpy.types.Operator):
             # show prop differently by cfg type
             match(cfg.get_type()):
                 case UTIL_bme.PrototypeShowcaseCfgsTypes.Integer:
-                    box_layout.prop(self.bme_struct_cfgs[cfg_index], 'prop_int', text = '')
+                    box_layout.prop(adder_cfgs_visitor[cfg_index], 'prop_int', text = '')
                 case UTIL_bme.PrototypeShowcaseCfgsTypes.Float:
-                    box_layout.prop(self.bme_struct_cfgs[cfg_index], 'prop_float', text = '')
+                    box_layout.prop(adder_cfgs_visitor[cfg_index], 'prop_float', text = '')
                 case UTIL_bme.PrototypeShowcaseCfgsTypes.Boolean:
-                    box_layout.prop(self.bme_struct_cfgs[cfg_index], 'prop_bool', text = '')
+                    box_layout.prop(adder_cfgs_visitor[cfg_index], 'prop_bool', text = '')
                 case UTIL_bme.PrototypeShowcaseCfgsTypes.Face:
                     # face will show a special layout (grid view)
                     grids = box_layout.grid_flow(
                         row_major=True, columns=3, even_columns=True, even_rows=True, align=True)
                     grids.alignment = 'CENTER'
                     grids.separator()
-                    grids.prop(self.bme_struct_cfgs[cfg_index + 0], 'prop_bool', text = 'Top') # top
+                    grids.prop(adder_cfgs_visitor[cfg_index + 0], 'prop_bool', text = 'Top') # top
-                    grids.prop(self.bme_struct_cfgs[cfg_index + 2], 'prop_bool', text = 'Front') # front
+                    grids.prop(adder_cfgs_visitor[cfg_index + 2], 'prop_bool', text = 'Front') # front
-                    grids.prop(self.bme_struct_cfgs[cfg_index + 4], 'prop_bool', text = 'Left') # left
+                    grids.prop(adder_cfgs_visitor[cfg_index + 4], 'prop_bool', text = 'Left') # left
                     grids.label(text = '', icon = 'CUBE')   # show a 3d cube as icon
-                    grids.prop(self.bme_struct_cfgs[cfg_index + 5], 'prop_bool', text = 'Right') # right
+                    grids.prop(adder_cfgs_visitor[cfg_index + 5], 'prop_bool', text = 'Right') # right
-                    grids.prop(self.bme_struct_cfgs[cfg_index + 3], 'prop_bool', text = 'Back') # back
+                    grids.prop(adder_cfgs_visitor[cfg_index + 3], 'prop_bool', text = 'Back') # back
-                    grids.prop(self.bme_struct_cfgs[cfg_index + 1], 'prop_bool', text = 'Bottom') # bottom
+                    grids.prop(adder_cfgs_visitor[cfg_index + 1], 'prop_bool', text = 'Bottom') # bottom
                     grids.separator()
 
         # show extra transform props

bbp_ng/OP_OBJECT_legacy_align.py

@@ -84,11 +84,13 @@ class BBP_OT_legacy_align(bpy.types.Operator):
 
         # check whether add new entry
         # if no selected axis, this alignment is invalid
-        entry: BBP_PG_legacy_align_history = self.align_history[-1]
+        histories: UTIL_functions.CollectionVisitor[BBP_PG_legacy_align_history]
+        histories = UTIL_functions.CollectionVisitor(self.align_history)
+        entry: BBP_PG_legacy_align_history = histories[-1]
         if entry.align_x == True or entry.align_y == True or entry.align_z == True:
             # valid one
             # add a new entry in history
-            self.align_history.add()
+            histories.add()
         else:
             # invalid one
             # reset all data to default
@@ -127,9 +129,11 @@ class BBP_OT_legacy_align(bpy.types.Operator):
         return _check_align_requirement()
 
     def invoke(self, context, event):
+        histories: UTIL_functions.CollectionVisitor[BBP_PG_legacy_align_history]
+        histories = UTIL_functions.CollectionVisitor(self.align_history)
         # clear history and add 1 entry for following functions
-        self.align_history.clear()
+        histories.clear()
-        self.align_history.add()
+        histories.add()
         # run execute() function
         return self.execute(context)
     
@@ -145,8 +149,9 @@ class BBP_OT_legacy_align(bpy.types.Operator):
         # If you place it at the end of this function, it doesn't work.
         context.view_layer.update()
         # iterate history to align objects
-        entry: BBP_PG_legacy_align_history
+        histories: UTIL_functions.CollectionVisitor[BBP_PG_legacy_align_history]
-        for entry in self.align_history:
+        histories = UTIL_functions.CollectionVisitor(self.align_history)
+        for entry in histories:
             _align_objects(
                 current_obj, target_objs,
                 entry.align_x, entry.align_y, entry.align_z,
@@ -157,7 +162,9 @@ class BBP_OT_legacy_align(bpy.types.Operator):
 
     def draw(self, context):
         # get last entry in history to show
-        entry: BBP_PG_legacy_align_history = self.align_history[-1]
+        histories: UTIL_functions.CollectionVisitor[BBP_PG_legacy_align_history]
+        histories = UTIL_functions.CollectionVisitor(self.align_history)
+        entry: BBP_PG_legacy_align_history = histories[-1]
 
         layout = self.layout
         col = layout.column()
@@ -183,7 +190,7 @@ class BBP_OT_legacy_align(bpy.types.Operator):
         conditional_disable_area.enabled = entry.align_x == True or entry.align_y == True or entry.align_z == True
         # show apply and counter
         conditional_disable_area.prop(self, 'apply_flag', text = 'Apply', icon = 'CHECKMARK', toggle = 1)
-        conditional_disable_area.label(text = f'Total {len(self.align_history) - 1} applied alignments')
+        conditional_disable_area.label(text = f'Total {len(histories) - 1} applied alignments')
 
 #region Core Functions
 

bbp_ng/OP_OBJECT_snoop_group_then_to_mesh.py

@@ -27,15 +27,10 @@ class BBP_OT_snoop_group_then_to_mesh(bpy.types.Operator):
             if bevel_obj is None: continue
 
             # copy bevel object group info into current object
-            # MARK: VirtoolsGroupsHelper is self-mutex.
-            # we only can operate one VirtoolsGroupsHelper at the same time.
-            # so we extract bevel object group infos then apply to target later.
-            group_infos: tuple[str, ...]
-            with PROP_virtools_group.VirtoolsGroupsHelper(bevel_obj) as bevel_gp:
-                group_infos = tuple(bevel_gp.iterate_groups())
             with PROP_virtools_group.VirtoolsGroupsHelper(obj) as this_gp:
                 this_gp.clear_groups()
-                this_gp.add_groups(group_infos)
+                with PROP_virtools_group.VirtoolsGroupsHelper(bevel_obj) as bevel_gp:
+                    this_gp.add_groups(bevel_gp.iterate_groups())
 
         # convert all selected object to mesh 
         # no matter the success of copying virtools group infos and whether selected object is curve

bbp_ng/PROP_ballance_element.py

@@ -104,8 +104,8 @@ class BBP_PG_ballance_element(bpy.types.PropertyGroup):
         type = bpy.types.Mesh
     ) # type: ignore
 
-def get_ballance_elements(scene: bpy.types.Scene) -> bpy.types.CollectionProperty:
+def get_ballance_elements(scene: bpy.types.Scene) -> UTIL_functions.CollectionVisitor[BBP_PG_ballance_element]:
-    return scene.ballance_elements
+    return UTIL_functions.CollectionVisitor(scene.ballance_elements)
 
 #endregion
 
@@ -224,7 +224,7 @@ class BallanceElementsHelper():
     This class should only have 1 instance at the same time. This class support `with` syntax to achieve this.
     This class frequently used in importing stage to create element placeholder.
     """
-    __mSingletonMutex: typing.ClassVar[bool] = False
+    __mSingletonMutex: typing.ClassVar[UTIL_functions.TinyMutex[bpy.types.Scene]] = UTIL_functions.TinyMutex()
     __mIsValid: bool
     __mAssocScene: bpy.types.Scene
     __mElementMap: dict[BallanceElementType, bpy.types.Mesh]
@@ -232,14 +232,11 @@ class BallanceElementsHelper():
     def __init__(self, assoc: bpy.types.Scene):
         self.__mElementMap = {}
         self.__mAssocScene = assoc
+        self.__mIsValid = False
 
         # check singleton
-        if BallanceElementsHelper.__mSingletonMutex:
+        BallanceElementsHelper.__mSingletonMutex.lock(self.__mAssocScene)
-            self.__mIsValid = False
-            raise UTIL_functions.BBPException('BallanceElementsHelper is mutex.')
-        
         # set validation and read ballance elements property
-        BallanceElementsHelper.__mSingletonMutex = True
         self.__mIsValid = True
         self.__read_from_ballance_element()
 
@@ -257,7 +254,7 @@ class BallanceElementsHelper():
             # write to ballance elements property and reset validation
             self.__write_to_ballance_elements()
             self.__mIsValid = False
-            BallanceElementsHelper.__mSingletonMutex = False
+            BallanceElementsHelper.__mSingletonMutex.unlock(self.__mAssocScene)
     
     def get_element(self, element_type: BallanceElementType) -> bpy.types.Mesh:
         if not self.is_valid():
@@ -276,8 +273,16 @@ class BallanceElementsHelper():
         self.__mElementMap[element_type] = new_mesh
         return new_mesh
 
+    def reset_elements(self) -> None:
+        if not self.is_valid():
+            raise UTIL_functions.BBPException('calling invalid BallanceElementsHelper')
+        
+        # reload all items
+        for elety, elemesh in self.__mElementMap.items():
+            _load_element(elemesh, elety)
+
     def __write_to_ballance_elements(self) -> None:
-        elements: bpy.types.CollectionProperty = get_ballance_elements(self.__mAssocScene)
+        elements = get_ballance_elements(self.__mAssocScene)
         elements.clear()
 
         for elety, elemesh in self.__mElementMap.items():
@@ -286,10 +291,9 @@ class BallanceElementsHelper():
             item.mesh_ptr = elemesh
 
     def __read_from_ballance_element(self) -> None:
-        elements: bpy.types.CollectionProperty = get_ballance_elements(self.__mAssocScene)
+        elements = get_ballance_elements(self.__mAssocScene)
         self.__mElementMap.clear()
 
-        item: BBP_PG_ballance_element
         for item in elements:
             # check requirements
             if item.mesh_ptr is None: continue
@@ -299,30 +303,6 @@ class BallanceElementsHelper():
             # add into map
             self.__mElementMap[element_type] = item.mesh_ptr
 
-def reset_ballance_elements(scene: bpy.types.Scene) -> None:
-    invalid_idx: list[int] = []
-    elements: bpy.types.CollectionProperty = get_ballance_elements(scene)
-
-    # re-load all elements
-    index: int = 0
-    item: BBP_PG_ballance_element
-    for item in elements:
-        elety: BallanceElementType | None = get_ballance_element_type_from_id(item.element_id)
-
-        # load or record invalid entry
-        if elety is None or item.mesh_ptr is None:
-            invalid_idx.append(index)
-        else:
-            _load_element(item.mesh_ptr, elety)
-
-        # inc counter
-        index += 1
-
-    # remove invalid one with reversed order
-    invalid_idx.reverse()
-    for idx in invalid_idx:
-        elements.remove(idx)
-
 #endregion
 
 #region Ballance Elements Representation
@@ -348,7 +328,8 @@ class BBP_OT_reset_ballance_elements(bpy.types.Operator):
         return context.scene is not None
     
     def execute(self, context):
-        reset_ballance_elements(context.scene)
+        with BallanceElementsHelper(context.scene) as helper:
+            helper.reset_elements()
         # show a window to let user know, not silence
         UTIL_functions.message_box(
             ('Reset OK.', ),

bbp_ng/PROP_bme_material.py

@@ -85,8 +85,8 @@ class BBP_PG_bme_material(bpy.types.PropertyGroup):
         type = bpy.types.Material
     ) # type: ignore
 
-def get_bme_materials(scene: bpy.types.Scene) -> bpy.types.CollectionProperty:
+def get_bme_materials(scene: bpy.types.Scene) -> UTIL_functions.CollectionVisitor[BBP_PG_bme_material]:
-    return scene.bme_materials
+    return UTIL_functions.CollectionVisitor(scene.bme_materials)
 
 #endregion
 
@@ -126,7 +126,7 @@ class BMEMaterialsHelper():
     This class should only have 1 instance at the same time. This class support `with` syntax to achieve this.
     This class frequently used in creating BME meshes.
     """
-    __mSingletonMutex: typing.ClassVar[bool] = False
+    __mSingletonMutex: typing.ClassVar[UTIL_functions.TinyMutex[bpy.types.Scene]] = UTIL_functions.TinyMutex()
     __mIsValid: bool
     __mAssocScene: bpy.types.Scene
     __mMaterialMap: dict[str, bpy.types.Material]
@@ -134,14 +134,11 @@ class BMEMaterialsHelper():
     def __init__(self, assoc: bpy.types.Scene):
         self.__mMaterialMap = {}
         self.__mAssocScene = assoc
+        self.__mIsValid = False
 
         # check singleton
-        if BMEMaterialsHelper.__mSingletonMutex:
+        BMEMaterialsHelper.__mSingletonMutex.lock(self.__mAssocScene)
-            self.__mIsValid = False
-            raise UTIL_functions.BBPException('BMEMaterialsHelper is mutex.')
-        
         # set validation and read ballance elements property
-        BMEMaterialsHelper.__mSingletonMutex = True
         self.__mIsValid = True
         self.__read_from_bme_materials()
 
@@ -159,7 +156,7 @@ class BMEMaterialsHelper():
             # write to ballance elements property and reset validation
             self.__write_to_bme_materials()
             self.__mIsValid = False
-            BMEMaterialsHelper.__mSingletonMutex = False
+            BMEMaterialsHelper.__mSingletonMutex.unlock(self.__mAssocScene)
     
     def get_material(self, preset_name: str) -> bpy.types.Material:
         if not self.is_valid():
@@ -179,7 +176,7 @@ class BMEMaterialsHelper():
         return new_mtl
 
     def __write_to_bme_materials(self) -> None:
-        mtls: bpy.types.CollectionProperty = get_bme_materials(self.__mAssocScene)
+        mtls = get_bme_materials(self.__mAssocScene)
         mtls.clear()
 
         for preset_name, mtl in self.__mMaterialMap.items():
@@ -188,10 +185,9 @@ class BMEMaterialsHelper():
             item.material_ptr = mtl
 
     def __read_from_bme_materials(self) -> None:
-        mtls: bpy.types.CollectionProperty = get_bme_materials(self.__mAssocScene)
+        mtls = get_bme_materials(self.__mAssocScene)
         self.__mMaterialMap.clear()
 
-        item: BBP_PG_bme_material
         for item in mtls:
             # check requirements
             if item.material_ptr is None: continue
@@ -200,7 +196,7 @@ class BMEMaterialsHelper():
 
 def reset_bme_materials(scene: bpy.types.Scene) -> None:
     invalid_idx: list[int] = []
-    mtls: bpy.types.CollectionProperty = get_bme_materials(scene)
+    mtls = get_bme_materials(scene)
 
     # re-load all elements
     index: int = 0

bbp_ng/PROP_virtools_group.py

@@ -10,8 +10,8 @@ class BBP_PG_virtools_group(bpy.types.PropertyGroup):
         default = ""
     ) # type: ignore
 
-def get_virtools_groups(obj: bpy.types.Object) -> bpy.types.CollectionProperty:
+def get_virtools_groups(obj: bpy.types.Object) -> UTIL_functions.CollectionVisitor[BBP_PG_virtools_group]:
-    return obj.virtools_groups
+    return UTIL_functions.CollectionVisitor(obj.virtools_groups)
 
 def get_active_virtools_groups(obj: bpy.types.Object) -> int:
     return obj.active_virtools_groups
@@ -26,7 +26,7 @@ class VirtoolsGroupsHelper():
     All Virtools group operations should be done by this class.
     Do NOT manipulate object's Virtools group properties directly.
     """
-    __mSingletonMutex: typing.ClassVar[bool] = False
+    __mSingletonMutex: typing.ClassVar[UTIL_functions.TinyMutex[bpy.types.Object]] = UTIL_functions.TinyMutex()
     __mIsValid: bool
     __mNoChange: bool ##< A bool indicate whether any change happended during lifetime. If no change, skip the writing when exiting.
     __mAssocObj: bpy.types.Object
@@ -36,14 +36,11 @@ class VirtoolsGroupsHelper():
         self.__mGroupsSet = set()
         self.__mAssocObj = assoc
         self.__mNoChange = True
+        self.__mIsValid = False
         
         # check singleton
-        if VirtoolsGroupsHelper.__mSingletonMutex:
+        VirtoolsGroupsHelper.__mSingletonMutex.lock(self.__mAssocObj)
-            self.__mIsValid = False
-            raise UTIL_functions.BBPException('VirtoolsGroupsHelper is mutex.')
-        
         # set validation and read ballance elements property
-        VirtoolsGroupsHelper.__mSingletonMutex = True
         self.__mIsValid = True
         self.__read_from_virtools_groups()
     
@@ -63,7 +60,7 @@ class VirtoolsGroupsHelper():
             if not self.__mNoChange:
                 self.__write_to_virtools_groups()
             self.__mIsValid = False
-            VirtoolsGroupsHelper.__mSingletonMutex = False
+            VirtoolsGroupsHelper.__mSingletonMutex.unlock(self.__mAssocObj)
     
     def __check_valid(self) -> None:
         if not self.is_valid():
@@ -127,7 +124,7 @@ class VirtoolsGroupsHelper():
         return len(self.__mGroupsSet)
     
     def __write_to_virtools_groups(self) -> None:
-        groups: bpy.types.CollectionProperty = get_virtools_groups(self.__mAssocObj)
+        groups = get_virtools_groups(self.__mAssocObj)
         sel: int = get_active_virtools_groups(self.__mAssocObj)
         groups.clear()
         
@@ -143,10 +140,9 @@ class VirtoolsGroupsHelper():
         set_active_virtools_groups(self.__mAssocObj, sel)
     
     def __read_from_virtools_groups(self) -> None:
-        groups: bpy.types.CollectionProperty = get_virtools_groups(self.__mAssocObj)
+        groups = get_virtools_groups(self.__mAssocObj)
         self.__mGroupsSet.clear()
         
-        item: BBP_PG_virtools_group
         for item in groups:
             self.__mGroupsSet.add(item.group_name)
 
@@ -306,7 +302,8 @@ class BBP_OT_add_virtools_group(bpy.types.Operator, SharedGroupNameInputProperti
     
     def execute(self, context):
         # add group
-        with VirtoolsGroupsHelper(context.object) as hlp:
+        obj = typing.cast(bpy.types.Object, context.object)
+        with VirtoolsGroupsHelper(obj) as hlp:
             hlp.add_group(self.general_get_group_name())
         return {'FINISHED'}
     
@@ -335,8 +332,9 @@ class BBP_OT_rm_virtools_group(bpy.types.Operator):
     
     def execute(self, context):
         # get selected group name first
-        obj = context.object
+        obj = typing.cast(bpy.types.Object, context.object)
-        item: BBP_PG_virtools_group = get_virtools_groups(obj)[get_active_virtools_groups(obj)]
+        groups = get_virtools_groups(obj)
+        item = groups[get_active_virtools_groups(obj)]
         gname: str = item.group_name
         # then delete it
         with VirtoolsGroupsHelper(obj) as hlp:
@@ -359,7 +357,8 @@ class BBP_OT_clear_virtools_groups(bpy.types.Operator):
         return wm.invoke_confirm(self, event)
     
     def execute(self, context):
-        with VirtoolsGroupsHelper(context.object) as hlp:
+        obj = typing.cast(bpy.types.Object, context.object)
+        with VirtoolsGroupsHelper(obj) as hlp:
             hlp.clear_groups()
         return {'FINISHED'}
 
@@ -384,7 +383,6 @@ class BBP_PT_virtools_groups(bpy.types.Panel):
             layout.label(text = 'Virtools Group is invalid on non-mesh object!', icon = 'ERROR')
 
         # draw main body
-        
         row = layout.row()
         row.template_list(
             "BBP_UL_virtools_groups", "", 

bbp_ng/UTIL_functions.py

@@ -173,3 +173,99 @@ class EnumPropHelper():
         # call to_str fct ptr
         return self.__mFctToStr(val)
 
+#region Blender Collection Visitor
+
+_TPropertyGroup = typing.TypeVar('_TPropertyGroup', bound = bpy.types.PropertyGroup)
+
+class CollectionVisitor(typing.Generic[_TPropertyGroup]):
+    """
+    This is a patch class for Blender collection property.
+    Blender collcetion property lack essential type hint and document.
+    So I create a wrapper for my personal use to reduce type hint errors raised by my linter.
+    """
+
+    __mSrcProp: bpy.types.CollectionProperty
+
+    def __init__(self, src_prop: bpy.types.CollectionProperty):
+        self.__mSrcProp = src_prop
+
+    def add(self) -> _TPropertyGroup:
+        """!
+        @brief Adds a new item to the collection.
+        @return The instance of newly created item.
+        """
+        return self.__mSrcProp.add()
+
+    def remove(self, index: int) -> None:
+        """!
+        @brief Removes the item at the specified index from the collection.
+        @param[in] index The index of the item to remove.
+        """
+        self.__mSrcProp.remove(index)
+
+    def move(self, from_index: int, to_index: int) -> None:
+        """!
+        @brief Moves an item from one index to another within the collection.
+        @param[in] from_index The current index of the item to move.
+        @param[in] to_index The target index where the item should be moved.
+        """
+        self.__mSrcProp.move(from_index, to_index)
+
+    def clear(self) -> None:
+        """!
+        @brief Clears all items from the collection.
+        """
+        self.__mSrcProp.clear()
+
+    def __len__(self) -> int:
+        return self.__mSrcProp.__len__()
+    def __getitem__(self, index: int | str) -> _TPropertyGroup:
+        return self.__mSrcProp.__getitem__(index)
+    def __setitem__(self, index: int | str, value: _TPropertyGroup) -> None:
+        self.__mSrcProp.__setitem__(index, value)
+    def __delitem__(self, index: int | str) -> None:
+        self.__mSrcProp.__delitem__(index)
+    def __iter__(self) -> typing.Iterator[_TPropertyGroup]:
+        return self.__mSrcProp.__iter__()
+    def __contains__(self, item: _TPropertyGroup) -> bool:
+        return self.__mSrcProp.__contains__(item)
+
+#endregion
+
+#region Tiny Mutex for With Context
+
+_TMutexObject = typing.TypeVar('_TMutexObject')
+
+class TinyMutex(typing.Generic[_TMutexObject]):
+    """
+    In this plugin, some class have "with" context feature.
+    However, it is essential to block any futher visiting if some "with" context are operating on some object.
+    This is the reason why this tiny mutex is designed.
+
+    Please note this class is not a real MUTEX.
+    We just want to make sure the resources only can be visited by one "with" context.
+    So it doesn't matter that we do not use lock before operating something.
+    """
+
+    __mProtectedObjects: set[_TMutexObject]
+
+    def __init__(self):
+        self.__mProtectedObjects = set()
+
+    def lock(self, obj: _TMutexObject) -> None:
+        if obj in self.__mProtectedObjects:
+            raise BBPException('It is not allowed that operate multiple "with" contexts on a single object.')
+        self.__mProtectedObjects.add(obj)
+
+    def try_lock(self, obj: _TMutexObject) -> bool:
+        if obj in self.__mProtectedObjects:
+            return False
+        self.__mProtectedObjects.add(obj)
+        return True
+
+    def unlock(self, obj: _TMutexObject) -> None:
+        if obj not in self.__mProtectedObjects:
+            raise BBPException('It is not allowed that unlock an non-existent object.')
+        self.__mProtectedObjects.remove(obj)
+
+#endregion