From 8dff4827896001f7fed841058b9e1794ce8f3df6 Mon Sep 17 00:00:00 2001
From: Adam Johnson <AdamJohnso@gmail.com>
Date: Fri, 11 Jan 2019 15:06:48 -0500
Subject: [PATCH] LOGICWIZ: don't leave junk node trees behind

---
 korman/properties/modifiers/avatar.py | 10 +++-------
 korman/properties/modifiers/base.py   | 19 ++++++++++++-------
 korman/properties/modifiers/gui.py    | 10 +++-------
 korman/properties/modifiers/region.py | 11 +++--------
 4 files changed, 21 insertions(+), 29 deletions(-)

diff --git a/korman/properties/modifiers/avatar.py b/korman/properties/modifiers/avatar.py
index 17bee7a..bb0110f 100644
--- a/korman/properties/modifiers/avatar.py
+++ b/korman/properties/modifiers/avatar.py
@@ -127,20 +127,16 @@ class PlasmaSittingBehavior(idprops.IDPropObjectMixin, PlasmaModifierProperties,
             raise ExportError("'{}': Sitting Behavior's clickable object is invalid".format(self.key_name))
 
         # Generate the logic nodes now
-        self.logicwiz(bo)
-
-        # Now, export the node tree
-        self.node_tree.export(exporter, bo, so)
+        with self.generate_logic(bo) as tree:
+            tree.export(exporter, bo, so)
 
     def harvest_actors(self):
         if self.facing_enabled:
             return (self.clickable_object.name,)
         return ()
 
-    def logicwiz(self, bo):
-        tree = self.node_tree
+    def logicwiz(self, bo, tree):
         nodes = tree.nodes
-        nodes.clear()
 
         # Sitting Modifier
         sittingmod = nodes.new("PlasmaSittingBehaviorNode")
diff --git a/korman/properties/modifiers/base.py b/korman/properties/modifiers/base.py
index ecab637..987e1de 100644
--- a/korman/properties/modifiers/base.py
+++ b/korman/properties/modifiers/base.py
@@ -16,6 +16,7 @@
 import abc
 import bpy
 from bpy.props import *
+from contextlib import contextmanager
 
 class PlasmaModifierProperties(bpy.types.PropertyGroup):
     def created(self):
@@ -70,16 +71,20 @@ class PlasmaModifierProperties(bpy.types.PropertyGroup):
 
 
 class PlasmaModifierLogicWiz:
-    @property
-    def node_tree(self):
-        name = self.key_name
+    @contextmanager
+    def generate_logic(self, bo, **kwargs):
+        name = kwargs.pop("name", self.key_name)
+        assert not "tree" in kwargs
+        tree = bpy.data.node_groups.new(name, "PlasmaNodeTree")
+        kwargs["tree"] = tree
         try:
-            return bpy.data.node_groups[name]
-        except LookupError:
-            return bpy.data.node_groups.new(name, "PlasmaNodeTree")
+            self.logicwiz(bo, **kwargs)
+            yield tree
+        finally:
+            bpy.data.node_groups.remove(tree)
 
     @abc.abstractmethod
-    def logicwiz(self, bo):
+    def logicwiz(self, bo, tree):
         pass
 
 
diff --git a/korman/properties/modifiers/gui.py b/korman/properties/modifiers/gui.py
index 2c42f9d..cc3adf7 100644
--- a/korman/properties/modifiers/gui.py
+++ b/korman/properties/modifiers/gui.py
@@ -163,19 +163,15 @@ class PlasmaJournalBookModifier(PlasmaModifierProperties, PlasmaModifierLogicWiz
             self.temp_rgn = self.clickable_region
 
         # Generate the logic nodes
-        self.logicwiz(bo, version)
-
-        # Export the node tree
-        self.node_tree.export(exporter, bo, so)
+        with self.generate_logic(bo, version=version) as tree:
+            tree.export(exporter, bo, so)
 
         # Get rid of our temporary clickable region
         if self.clickable_region is None:
             bpy.context.scene.objects.unlink(self.temp_rgn)
 
-    def logicwiz(self, bo, version):
-        tree = self.node_tree
+    def logicwiz(self, bo, tree, version):
         nodes = tree.nodes
-        nodes.clear()
 
         # Assign journal script based on target version
         journal_pfm = journal_pfms[version]
diff --git a/korman/properties/modifiers/region.py b/korman/properties/modifiers/region.py
index 5db0098..7af59e6 100644
--- a/korman/properties/modifiers/region.py
+++ b/korman/properties/modifiers/region.py
@@ -140,16 +140,11 @@ class PlasmaFootstepRegion(PlasmaModifierProperties, PlasmaModifierLogicWiz):
                           default="hull")
 
     def export(self, exporter, bo, so):
-        # Generate the logic nodes now
-        self.logicwiz(bo)
-
-        # Now, export the node tree
-        self.node_tree.export(exporter, bo, so)
+        with self.generate_logic(bo) as tree:
+            tree.export(exporter, bo, so)
 
-    def logicwiz(self, bo):
-        tree = self.node_tree
+    def logicwiz(self, bo, tree):
         nodes = tree.nodes
-        nodes.clear()
 
         # Region Sensor
         volsens = nodes.new("PlasmaVolumeSensorNode")