Add asserts to prevent people from setting box.parentData.position or box.size except during layout.

sky/sdk/lib/framework/rendering/object.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import '../node.dart';
 import '../scheduler.dart' as scheduler;
 import 'dart:math' as math;
 import 'dart:sky' as sky;
 import 'dart:sky' show Point, Size, Rect, Color, Paint, Path;
 export 'dart:sky' show Point, Size, Rect, Color, Paint, Path;
@@ skipping 31 matching lines @@
 abstract class RenderObject extends AbstractNode {
 
   // LAYOUT
 
   // parentData is only for use by the RenderObject that actually lays this
   // node out, and any other nodes who happen to know exactly what
   // kind of node that is.
   dynamic parentData; // TODO(ianh): change the type of this back to ParentData once the analyzer is cleverer
   void setParentData(RenderObject child) {
     // override this to setup .parentData correctly for your class
-    assert(!_debugDoingLayout);
+    assert(!debugDoingLayout);
     assert(!debugDoingPaint);
     if (child.parentData is! ParentData)
       child.parentData = new ParentData();
   }
 
   void adoptChild(RenderObject child) { // only for use by subclasses
     // call this whenever you decide a node is a child
-    assert(!_debugDoingLayout);
+    assert(!debugDoingLayout);
     assert(!debugDoingPaint);
     assert(child != null);
     setParentData(child);
     super.adoptChild(child);
     markNeedsLayout();
   }
   void dropChild(RenderObject child) { // only for use by subclasses
-    assert(!_debugDoingLayout);
+    assert(!debugDoingLayout);
     assert(!debugDoingPaint);
     assert(child != null);
     assert(child.parentData != null);
     child.parentData.detach();
     if (child._relayoutSubtreeRoot != child) {
       child._relayoutSubtreeRoot = null;
       child._needsLayout = true;
     }
     super.dropChild(child);
     markNeedsLayout();
   }
 
   static List<RenderObject> _nodesNeedingLayout = new List<RenderObject>();
   static bool _debugDoingLayout = false;
+  static bool get debugDoingLayout => _debugDoingLayout;
   bool _needsLayout = true;
   bool get needsLayout => _needsLayout;
   RenderObject _relayoutSubtreeRoot;
   dynamic _constraints;
   dynamic get constraints => _constraints;
   bool debugAncestorsAlreadyMarkedNeedsLayout() {
     if (_relayoutSubtreeRoot == null)
       return true; // we haven't yet done layout even once, so there's nothing for us to do
     RenderObject node = this;
     while (node != _relayoutSubtreeRoot) {
       assert(node._relayoutSubtreeRoot == _relayoutSubtreeRoot);
       assert(node.parent != null);
       node = node.parent as RenderObject;
       if (!node._needsLayout)
         return false;
     }
     assert(node._relayoutSubtreeRoot == node);
     return true;
   }
   void markNeedsLayout() {
-    assert(!_debugDoingLayout);
+    assert(!debugDoingLayout);
     assert(!debugDoingPaint);
     if (_needsLayout) {
       assert(debugAncestorsAlreadyMarkedNeedsLayout());
       return;
     }
     _needsLayout = true;
     assert(_relayoutSubtreeRoot != null);
     if (_relayoutSubtreeRoot != this) {
       final parent = this.parent; // TODO(ianh): Remove this once the analyzer is cleverer
       assert(parent is RenderObject);
@@ skipping 328 matching lines @@
     int count = 1;
     ChildType child = _firstChild;
     while (child != null) {
       result += '${prefix}child ${count}: ${child.toString(prefix)}';
       count += 1;
       child = child.parentData.nextSibling;
     }
     return result;
   }
 }