Add custom view iteration to guide

guide/master/src/going-further/custom-views.md

@@ -7,6 +7,7 @@ View bundles only contain other views while wild views can contain other types.
 
 Example of a View Bundle:
 ```rust, noplaypen
+#[derive(Borrow, BorrowInfo)]
 struct Hierarchy<'v> {
     entities: EntitiesViewMut<'v>,
     parents: ViewMut<'v, Parent>,
@@ -19,7 +20,17 @@ Example of a Wild View:
 struct RandomNumber(u64);
 ```
 
-### Concrete example
+### Iteration
+
+View bundles can be iterated directly by deriving the `IntoIter` trait.
+
+```rust, noplaypen
+{{#include ../../../../tests/book/custom_view.rs:into_iter}}
+```
+
+All attributes are optional.
+
+## Concrete example
 
 When creating a frame with any low level api there is always some boilerplate. We'll look at how custom views can help for `wgpu`.
 

tests/book/custom_view.rs

@@ -0,0 +1,31 @@
+use shipyard::{Borrow, BorrowInfo, Component, EntitiesViewMut, IntoIter, ViewMut, World};
+
+#[test]
+#[rustfmt::skip]
+#[allow(unused)]
+fn view() {
+#[derive(Component)]
+struct Parent;
+#[derive(Component)]
+struct Child;
+
+// ANCHOR: into_iter
+#[derive(Borrow, BorrowInfo, IntoIter)]
+#[shipyard(item_name = "Node")]
+struct Hierarchy<'v> {
+    #[shipyard(item_field_skip)]
+    entities: EntitiesViewMut<'v>,
+    #[shipyard(item_field_name = "parent")]
+    parents: ViewMut<'v, Parent>,
+    #[shipyard(item_field_name = "child")]
+    children: ViewMut<'v, Child>,
+}
+
+let world = World::new();
+
+world.run(|mut hierarchy: Hierarchy| {
+    for Node { parent, child } in hierarchy.iter() {
+    }
+});
+// ANCHOR_END: into_iter
+}

tests/book/mod.rs

@@ -2,6 +2,7 @@ use shipyard::{track, Component};
 
 mod add_components;
 mod add_entity;
+mod custom_view;
 mod delete_components;
 mod delete_entity;
 mod get;