block: Make BlockAttributes #[non_exhaustive].

To construct an instance, `block::Builder()` can now build attributes.

CHANGELOG.md

@@ -13,6 +13,10 @@
 
 ### Changed
 
+- `all-is-cubes` library:
+    - `block::BlockAttributes` is now a non-exhaustive struct.
+      `BlockAttributes` literals should be replaced with `block::Builder::build_attributes()`.
+
 - `all-is-cubes-ui` library:
     - `apps::Session::settings()` replaces `graphics_options_mut()`.
 

all-is-cubes-content/src/city.rs

@@ -7,7 +7,8 @@ use itertools::Itertools;
 use rand::seq::SliceRandom as _;
 use rand::{Rng, SeedableRng as _};
 
-use all_is_cubes::block::{self, text::Font, BlockAttributes, Resolution::*, AIR};
+use all_is_cubes::arcstr::literal;
+use all_is_cubes::block::{self, text::Font, Resolution::*, AIR};
 use all_is_cubes::character::Spawn;
 use all_is_cubes::color_block;
 use all_is_cubes::content::palette;
@@ -569,11 +570,10 @@ fn place_one_exhibit<I: Instant>(
                     bounds_for_info_voxels,
                     universe.insert_anonymous(exhibit_info_space),
                     info_resolution,
-                    [BlockAttributes {
-                        display_name: "Exhibit Name".into(),
-                        ..Default::default()
-                    }
-                    .into()],
+                    [block::Block::builder()
+                        .display_name(literal!("Exhibit Name"))
+                        .build_attributes()
+                        .into()],
                 ))),
             ],
         });

all-is-cubes-content/src/city/exhibits/knot.rs

@@ -69,10 +69,11 @@ fn KNOT(ctx: Context<'_>) {
         resolution,
         txn.insert_anonymous(drawing_space),
         &mut |block| {
-            block.with_modifier(BlockAttributes {
-                display_name: ctx.exhibit.name.into(),
-                ..BlockAttributes::default()
-            })
+            block.with_modifier(
+                Block::builder()
+                    .display_name(ctx.exhibit.name)
+                    .build_attributes(),
+            )
         },
     )?;
     Ok((space, txn))

all-is-cubes-content/src/city/exhibits/prelude.rs

@@ -12,8 +12,7 @@ pub(super) use rand::SeedableRng as _;
 
 pub(super) use all_is_cubes::arcstr::{self, literal};
 pub(super) use all_is_cubes::block::{
-    self, space_to_blocks, text, Block, BlockAttributes, BlockCollision, Composite,
-    CompositeOperator, Move,
+    self, space_to_blocks, text, Block, BlockCollision, Composite, CompositeOperator, Move,
     Resolution::{self, *},
     RotationPlacementRule, Zoom, AIR,
 };

all-is-cubes/src/block/attributes.rs

@@ -149,8 +149,7 @@ macro_rules! attribute_builder_method {
 /// `BlockAttributes::default()` will produce a reasonable set of defaults for “ordinary”
 /// blocks.
 #[derive(Clone, Eq, Hash, PartialEq)]
-#[expect(clippy::exhaustive_structs)]
-// TODO: Make this non_exhaustive but give users a way to construct it easily, possibly via block::Builder.
+#[non_exhaustive]
 #[macro_rules_attribute::derive(derive_attribute_helpers!)]
 pub struct BlockAttributes {
     /// The name that should be displayed to players.

all-is-cubes/src/block/builder.rs

@@ -15,9 +15,13 @@ use crate::universe::{Handle, Name, Universe, UniverseTransaction};
 
 /// Tool for constructing [`Block`] values conveniently.
 ///
+/// It can also be used to construct [`BlockAttributes`] values.
+///
 /// To create one, call [`Block::builder()`].
 /// ([`Builder::default()`] is also available.)
 ///
+/// # Example
+///
 /// ```
 /// use all_is_cubes::block::{Block, EvaluatedBlock};
 /// use all_is_cubes::math::Rgba;
@@ -40,9 +44,11 @@ use crate::universe::{Handle, Name, Universe, UniverseTransaction};
 #[derive(Clone, Debug, Eq, PartialEq)]
 #[must_use]
 pub struct Builder<P, Txn> {
-    // public so that `BlockAttributes`'s macros can define methods for us
+    /// public so that `BlockAttributes`'s macros can define methods for us
     pub(in crate::block) attributes: BlockAttributes,
+
     primitive_builder: P,
+
     modifiers: Vec<Modifier>,
 
     /// If this is a [`UniverseTransaction`], then it must be produced for the caller to execute.
@@ -66,6 +72,21 @@ impl Builder<NeedsPrimitive, ()> {
             transaction: (),
         }
     }
+
+    /// Returns a [`BlockAttributes`] instead of building a block with those attributes.
+    ///
+    /// Panics if any modifiers were added to the builder.
+    #[track_caller]
+    pub fn build_attributes(self) -> BlockAttributes {
+        let Self {
+            attributes,
+            primitive_builder: NeedsPrimitive,
+            modifiers,
+            transaction: (),
+        } = self;
+        assert_eq!(modifiers, []);
+        attributes
+    }
 }
 
 impl<P, Txn> Builder<P, Txn> {

all-is-cubes/tests/alloc.rs

@@ -11,28 +11,30 @@ use all_is_cubes::universe::Universe;
 
 #[test]
 fn clone_block_attributes() {
-    let original = BlockAttributes {
+    // TODO: Ideally this would be a struct literal with every field,
+    // but we define BlockAttributes as #[non_exhaustive]. Find a way to prove this is complete.
+    let original: BlockAttributes = block::Block::builder()
+        //
         // These fields are refcounted or `Copy` and will not allocate when cloned
-        display_name: arcstr::literal!("hello"),
-        selectable: true,
-        animation_hint: block::AnimationHint::UNCHANGING,
-
-        placement_action: Some(block::PlacementAction {
+        .display_name(arcstr::literal!("hello"))
+        .selectable(true)
+        .animation_hint(block::AnimationHint::UNCHANGING)
+        .placement_action(block::PlacementAction {
             operation: Operation::Become(block::AIR),
             in_front: false,
-        }),
-        tick_action: Some(block::TickAction::from(Operation::Become(block::AIR))),
-        activation_action: Some(Operation::Become(block::AIR)),
-
+        })
+        .tick_action(block::TickAction::from(Operation::Become(block::AIR)))
+        .activation_action(Operation::Become(block::AIR))
+        //
         // TODO(inventory): This field will allocate when cloned if it is nonempty,
         // and we should fix that and test it.
-        inventory: inv::InvInBlock::default(),
-
+        .inventory_config(inv::InvInBlock::default())
+        //
         // These fields currently will never allocate when cloned
-        rotation_rule: block::RotationPlacementRule::Never,
-    };
-    let mut clone = None;
+        .rotation_rule(block::RotationPlacementRule::Never)
+        .build_attributes();
 
+    let mut clone = None;
     assert_no_alloc(|| {
         clone = Some(original.clone());
     });