Rigify: internal API enhancements.

Add a LazyRigComponent class that has to be explicitly enabled
to start receiving callbacks.

Support calling GeneratorPlugin instance callbacks in the same
stage they were created.

rigify/base_generate.py

@@ -31,6 +31,7 @@ from .utils.misc import clone_parameters, assign_parameters
 
 from . import base_rig
 
+from itertools import count
 
 #=============================================
 # Generator Plugin
@@ -284,13 +285,24 @@ class BaseGenerator:
 
         self.stage = method_name
 
-        for rig in [*self.rig_list, *self.plugin_list]:
+        for rig in self.rig_list:
             rig.rigify_invoke_stage(method_name)
 
             assert(self.context.active_object == self.obj)
             assert(self.obj.mode == 'OBJECT')
             assert(num_bones == len(self.obj.data.bones))
 
+        # Allow plugins to be added to the end of the list on the fly
+        for i in count(0):
+            if i >= len(self.plugin_list):
+                break
+
+            self.plugin_list[i].rigify_invoke_stage(method_name)
+
+            assert(self.context.active_object == self.obj)
+            assert(self.obj.mode == 'OBJECT')
+            assert(num_bones == len(self.obj.data.bones))
+
 
     def __run_edit_stage(self, method_name):
         assert(self.context.active_object == self.obj)
@@ -299,13 +311,24 @@ class BaseGenerator:
 
         self.stage = method_name
 
-        for rig in [*self.rig_list, *self.plugin_list]:
+        for rig in self.rig_list:
             rig.rigify_invoke_stage(method_name)
 
             assert(self.context.active_object == self.obj)
             assert(self.obj.mode == 'EDIT')
             assert(num_bones == len(self.obj.data.edit_bones))
 
+        # Allow plugins to be added to the end of the list on the fly
+        for i in count(0):
+            if i >= len(self.plugin_list):
+                break
+
+            self.plugin_list[i].rigify_invoke_stage(method_name)
+
+            assert(self.context.active_object == self.obj)
+            assert(self.obj.mode == 'EDIT')
+            assert(num_bones == len(self.obj.data.edit_bones))
+
 
     def invoke_initialize(self):
         self.__run_object_stage('initialize')

rigify/base_rig.py

@@ -267,14 +267,25 @@ class RigUtility(BoneUtilityMixin, MechanismUtilityMixin):
         self.owner.register_new_bone(new_name, old_name)
 
 
-class RigComponent(GenerateCallbackHost, RigUtility):
-    """Base class for utility classes that generate part of a rig using callbacks."""
+class LazyRigComponent(GenerateCallbackHost, RigUtility):
+    """Base class for utility classes that generate part of a rig using callbacks. Starts as disabled."""
     def __init__(self, owner):
         super().__init__(owner)
 
-        self.owner.rigify_sub_objects = objects = self.owner.rigify_sub_objects or []
+        self.is_component_enabled = False
+
+    def enable_component(self):
+        if not self.is_component_enabled:
+            self.is_component_enabled = True
+            self.owner.rigify_sub_objects = objects = self.owner.rigify_sub_objects or []
+            objects.append(self)
+
 
-        objects.append(self)
+class RigComponent(LazyRigComponent):
+    """Base class for utility classes that generate part of a rig using callbacks."""
+    def __init__(self, owner):
+        super().__init__(owner)
+        self.enable_component()
 
 
 #=============================================