Fill out some more documentation about building RenderBox subclasses.

sky/sdk/lib/rendering/block.dart

Index: sky/sdk/lib/rendering/block.dart
diff --git a/sky/sdk/lib/rendering/block.dart b/sky/sdk/lib/rendering/block.dart
index 4d163db4a29001d57e482ec699dc52da7ed81dc0..cc6859e77268b454323e9aef93175132e9c8f172 100644
--- a/sky/sdk/lib/rendering/block.dart
+++ b/sky/sdk/lib/rendering/block.dart
@@ -19,7 +19,8 @@ class RenderBlock extends RenderBox with ContainerRenderObjectMixin<RenderBox, B
     List<RenderBox> children
   }) {
     if (children != null)
-      children.forEach((child) { add(child); });
+      for (RenderBox child in children)

[hansmuller, 2015/06/24 20:30:14]

Maybe just define addAll(children) in ContainerRenderObjectMixin and have it do
all of this, even the null check?

[Hixie, 2015/06/25 19:15:31]

Good idea. Done.

+        add(child);

[hansmuller, 2015/06/24 19:53:31]

https://www.dartlang.org/articles/style-guide/#do-use-curly-braces-for-all-fl...

[Hixie, 2015/06/25 19:15:31]

I updated our style guide to disagree with this. Adding extra braces where
they're not needed harms readability. There's no dangling-else issue here.

   }
 
   void setParentData(RenderBox child) {

[hansmuller, 2015/06/24 20:32:49]

Could setParentData() be defined in RenderBoxContainerDefaultsMixin?

[Hixie, 2015/06/25 19:15:32]

Sadly not. You can't call "new" on a generic type argument for some reason. If
you could, it'd be in the Container mixin. (The Defaults mixin is just for some
helper functions, it shouldn't override actual methods.)