A bit more pythonic way of using the items callback in node categories. The category.items attribute is now a function taking a context parameter instead of a property. This can be used for checking validity, e.g. for doing node group recursion checks, and filter out unusable items.

release/scripts/modules/nodeitems_utils.py

@@ -26,21 +26,17 @@ class NodeCategory():
     def poll(cls, context):
         return True
 
-    @property
+    def __init__(self, identifier, name, description="", items=None):
-    def items(self):
-        if hasattr(self, '_items'):
-            return self._items
-        elif hasattr(self, '_itemfunc'):
-            return self._itemfunc(self)
-
-    def __init__(self, identifier, name, description="", items=[]):
         self.identifier = identifier
         self.name = name
         self.description = description
-        if callable(items):
+
-            self._itemfunc = items
+        if items is None:
+            self.items = lambda context: []
+        elif callable(items):
+            self.items = items
         else:
-            self._items = items
+            self.items = lambda context: items
 
 class NodeItem():
     def __init__(self, nodetype, label=None, settings={}):
@@ -69,7 +65,7 @@ def register_node_categories(identifier, cat_list):
         layout = self.layout
         col = layout.column()
         default_context = bpy.app.translations.contexts.default
-        for item in self.category.items:
+        for item in self.category.items(context):
             op = col.operator("node.add_node", text=item.label, text_ctxt=default_context)
             op.type = item.nodetype
             op.use_transform = True

release/scripts/startup/nodeitems_builtins.py

@@ -17,7 +17,6 @@
 # ##### END GPL LICENSE BLOCK #####
 
 # <pep8 compliant>
-import bpy
 import nodeitems_utils
 from nodeitems_utils import NodeCategory, NodeItem
 
@@ -47,18 +46,24 @@ class TextureNodeCategory(NodeCategory):
         return context.space_data.tree_type == 'TextureNodeTree'
 
 
-def compositor_node_group_items(self):
+# maps node tree type to group node type
-    return [NodeItem('CompositorNodeGroup', group.name, { "node_tree" : "bpy.data.node_groups['%s']" % group.name })
+node_tree_group_type = {
-            for group in bpy.data.node_groups if group.bl_idname == 'CompositorNodeTree']
+    'CompositorNodeTree'    : 'CompositorNodeGroup',
+    'ShaderNodeTree'        : 'ShaderNodeGroup',
+    'TextureNodeTree'       : 'TextureNodeGroup',
+    }
+# generic node group items generator for shader, compositor and texture node groups
+def node_group_items(context):
+    space = context.space_data
+    if not space:
+        return
+    ntree = space.edit_tree
+    if not ntree:
+        return
 
-# Note: node groups not distinguished by old/new shader nodes
+    for group in context.blend_data.node_groups:
-def shader_node_group_items(self):
+        if group.bl_idname == ntree.bl_idname:
-    return [NodeItem('ShaderNodeGroup', group.name, { "node_tree" : "bpy.data.node_groups['%s']" % group.name })
+            yield NodeItem(node_tree_group_type[group.bl_idname], group.name, { "node_tree" : "bpy.data.node_groups['%s']" % group.name })
-            for group in bpy.data.node_groups if group.bl_idname == 'ShaderNodeTree']
-
-def texture_node_group_items(self):
-    return [NodeItem('TextureNodeGroup', group.name, { "node_tree" : "bpy.data.node_groups['%s']" % group.name })
-            for group in bpy.data.node_groups if group.bl_idname == 'TextureNodeTree']
 
 
 # All standard node categories currently used in nodes.
@@ -99,7 +104,7 @@ shader_node_categories = [
         ]),
     ShaderOldNodeCategory("SH_SCRIPT", "Script", items=[
         ]),
-    ShaderOldNodeCategory("SH_GROUP", "Group", items=shader_node_group_items),
+    ShaderOldNodeCategory("SH_GROUP", "Group", items=node_group_items),
     ShaderOldNodeCategory("SH_LAYOUT", "Layout", items=[
         NodeItem("NodeFrame"),
         ]),
@@ -182,7 +187,7 @@ shader_node_categories = [
     ShaderNewNodeCategory("SH_NEW_SCRIPT", "Script", items=[
         NodeItem("ShaderNodeScript"),
         ]),
-    ShaderNewNodeCategory("SH_NEW_GROUP", "Group", items=shader_node_group_items),
+    ShaderNewNodeCategory("SH_NEW_GROUP", "Group", items=node_group_items),
     ShaderNewNodeCategory("SH_NEW_LAYOUT", "Layout", items=[
         NodeItem("NodeFrame"),
         ]),
@@ -287,7 +292,7 @@ compositor_node_categories = [
         NodeItem("CompositorNodeTransform"),
         NodeItem("CompositorNodeStabilize"),
         ]),
-    CompositorNodeCategory("CMP_GROUP", "Group", items=compositor_node_group_items),
+    CompositorNodeCategory("CMP_GROUP", "Group", items=node_group_items),
     CompositorNodeCategory("CMP_LAYOUT", "Layout", items = [
         NodeItem("NodeFrame"),
         NodeItem("CompositorNodeSwitch"),
@@ -342,7 +347,7 @@ texture_node_categories = [
         NodeItem("TextureNodeTranslate"),
         NodeItem("TextureNodeRotate"),
         ]),
-    TextureNodeCategory("TEX_GROUP", "Group", items=texture_node_group_items),
+    TextureNodeCategory("TEX_GROUP", "Group", items=node_group_items),
     TextureNodeCategory("TEX_LAYOUT", "Layout", items = [
         NodeItem("NodeFrame"),
         ]),