Add two comments on impl_add macro

akern40 · akern40 · commit 312c744ce02a · 2026-01-10T11:53:24.000-05:00
diff --git a/src/layout/dimensionality.rs b/src/layout/dimensionality.rs
@@ -153,13 +153,15 @@ def_d_aliases!(
 /// Implement addition for a given dimensionality.
 macro_rules! impl_add {
     ($left:literal, ($($right:literal),*), ddyn: ($($rightd:literal),*)) => {
+        // $left + $right still gets you a compile-time dimension
         $(
             impl DAdd<NDim<$right>> for NDim<$left>
             {
                 type Output = NDim<{$left + $right}>;
             }
         )*
 
+        // $left + $rightd gets you a dynamic dimensionality
         $(
             impl DAdd<NDim<$rightd>> for NDim<$left>
             {

Original file line number	Diff line number	Diff line change
`@@ -153,13 +153,15 @@ def_d_aliases!(`
`153`	`153`	`/// Implement addition for a given dimensionality.`
`154`	`154`	`macro_rules! impl_add {`
`155`	`155`	`($left:literal, ($($right:literal),), ddyn: ($($rightd:literal),)) => {`
	`156`	`+ // $left + $right still gets you a compile-time dimension`
`156`	`157`	`$(`
`157`	`158`	`impl DAdd<NDim<$right>> for NDim<$left>`
`158`	`159`	`{`
`159`	`160`	`type Output = NDim<{$left + $right}>;`
`160`	`161`	`}`
`161`	`162`	`)*`
`162`	`163`
	`164`	`+ // $left + $rightd gets you a dynamic dimensionality`
`163`	`165`	`$(`
`164`	`166`	`impl DAdd<NDim<$rightd>> for NDim<$left>`
`165`	`167`	`{`