From 0541f13b268997c2ffb3783586dbd319a9973147 Mon Sep 17 00:00:00 2001
From: Benjamin Saunders <ben.e.saunders@gmail.com>
Date: Sun, 12 Sep 2021 10:52:46 -0700
Subject: [PATCH] Concise Debug impls

Replace the verbose derived (or nearly equivalent) Debug impls for
several newtypes with explicit impls that forward to the inner type,
making readable diagnostics logging much easier.
---
 src/base/matrix.rs          |  5 +----
 src/base/unit.rs            |  9 ++++++++-
 src/geometry/point.rs       | 11 ++++++++++-
 src/geometry/quaternion.rs  |  8 +++++++-
 src/geometry/rotation.rs    |  7 ++++++-
 src/geometry/transform.rs   | 13 +++++++++++--
 src/geometry/translation.rs |  7 ++++++-
 tests/core/matrix.rs        |  4 ++--
 8 files changed, 51 insertions(+), 13 deletions(-)

diff --git a/src/base/matrix.rs b/src/base/matrix.rs
index 13413dbf..8d17a02d 100644
--- a/src/base/matrix.rs
+++ b/src/base/matrix.rs
@@ -195,10 +195,7 @@ pub struct Matrix<T, R, C, S> {
 
 impl<T, R: Dim, C: Dim, S: fmt::Debug> fmt::Debug for Matrix<T, R, C, S> {
     fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
-        formatter
-            .debug_struct("Matrix")
-            .field("data", &self.data)
-            .finish()
+        self.data.fmt(formatter)
     }
 }
 
diff --git a/src/base/unit.rs b/src/base/unit.rs
index cd32b44b..8d548687 100644
--- a/src/base/unit.rs
+++ b/src/base/unit.rs
@@ -1,3 +1,4 @@
+use std::fmt;
 #[cfg(feature = "abomonation-serialize")]
 use std::io::{Result as IOResult, Write};
 use std::ops::Deref;
@@ -24,11 +25,17 @@ use crate::{Dim, Matrix, OMatrix, RealField, Scalar, SimdComplexField, SimdRealF
 /// and [`UnitQuaternion`](crate::UnitQuaternion); both built on top of `Unit`.  If you are interested
 /// in their documentation, read their dedicated pages directly.
 #[repr(transparent)]
-#[derive(Clone, Hash, Debug, Copy)]
+#[derive(Clone, Hash, Copy)]
 pub struct Unit<T> {
     pub(crate) value: T,
 }
 
+impl<T: fmt::Debug> fmt::Debug for Unit<T> {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        self.value.fmt(formatter)
+    }
+}
+
 #[cfg(feature = "bytemuck")]
 unsafe impl<T> bytemuck::Zeroable for Unit<T> where T: bytemuck::Zeroable {}
 
diff --git a/src/geometry/point.rs b/src/geometry/point.rs
index 69022671..7930e8fb 100644
--- a/src/geometry/point.rs
+++ b/src/geometry/point.rs
@@ -40,7 +40,7 @@ use std::mem::MaybeUninit;
 /// may have some other methods, e.g., `isometry.inverse_transform_point(&point)`. See the documentation
 /// of said transformations for details.
 #[repr(C)]
-#[derive(Debug, Clone)]
+#[derive(Clone)]
 pub struct OPoint<T: Scalar, D: DimName>
 where
     DefaultAllocator: Allocator<T, D>,
@@ -49,6 +49,15 @@ where
     pub coords: OVector<T, D>,
 }
 
+impl<T: Scalar + fmt::Debug, D: DimName> fmt::Debug for OPoint<T, D>
+where
+    DefaultAllocator: Allocator<T, D>,
+{
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        self.coords.as_slice().fmt(formatter)
+    }
+}
+
 impl<T: Scalar + hash::Hash, D: DimName> hash::Hash for OPoint<T, D>
 where
     DefaultAllocator: Allocator<T, D>,
diff --git a/src/geometry/quaternion.rs b/src/geometry/quaternion.rs
index 6d53863a..968a9e18 100755
--- a/src/geometry/quaternion.rs
+++ b/src/geometry/quaternion.rs
@@ -27,12 +27,18 @@ use crate::geometry::{Point3, Rotation};
 /// A quaternion. See the type alias `UnitQuaternion = Unit<Quaternion>` for a quaternion
 /// that may be used as a rotation.
 #[repr(C)]
-#[derive(Debug, Copy, Clone)]
+#[derive(Copy, Clone)]
 pub struct Quaternion<T> {
     /// This quaternion as a 4D vector of coordinates in the `[ x, y, z, w ]` storage order.
     pub coords: Vector4<T>,
 }
 
+impl<T: fmt::Debug> fmt::Debug for Quaternion<T> {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        self.coords.as_slice().fmt(formatter)
+    }
+}
+
 impl<T: Scalar + Hash> Hash for Quaternion<T> {
     fn hash<H: Hasher>(&self, state: &mut H) {
         self.coords.hash(state)
diff --git a/src/geometry/rotation.rs b/src/geometry/rotation.rs
index 3ac3ca57..e1da8d67 100755
--- a/src/geometry/rotation.rs
+++ b/src/geometry/rotation.rs
@@ -54,11 +54,16 @@ use crate::geometry::Point;
 /// * [Conversion to a matrix <span style="float:right;">`matrix`, `to_homogeneous`…</span>](#conversion-to-a-matrix)
 ///
 #[repr(C)]
-#[derive(Debug)]
 pub struct Rotation<T, const D: usize> {
     matrix: SMatrix<T, D, D>,
 }
 
+impl<T: fmt::Debug, const D: usize> fmt::Debug for Rotation<T, D> {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        self.matrix.fmt(formatter)
+    }
+}
+
 impl<T: Scalar + hash::Hash, const D: usize> hash::Hash for Rotation<T, D>
 where
     <DefaultAllocator as Allocator<T, Const<D>, Const<D>>>::Buffer: hash::Hash,
diff --git a/src/geometry/transform.rs b/src/geometry/transform.rs
index f9dbeb51..d87a815d 100755
--- a/src/geometry/transform.rs
+++ b/src/geometry/transform.rs
@@ -1,6 +1,6 @@
 use approx::{AbsDiffEq, RelativeEq, UlpsEq};
 use std::any::Any;
-use std::fmt::Debug;
+use std::fmt::{self, Debug};
 use std::hash;
 use std::marker::PhantomData;
 
@@ -157,7 +157,6 @@ super_tcategory_impl!(
 /// It is stored as a matrix with dimensions `(D + 1, D + 1)`, e.g., it stores a 4x4 matrix for a
 /// 3D transformation.
 #[repr(C)]
-#[derive(Debug)]
 pub struct Transform<T: RealField, C: TCategory, const D: usize>
 where
     Const<D>: DimNameAdd<U1>,
@@ -167,6 +166,16 @@ where
     _phantom: PhantomData<C>,
 }
 
+impl<T: RealField + Debug, C: TCategory, const D: usize> Debug for Transform<T, C, D>
+where
+    Const<D>: DimNameAdd<U1>,
+    DefaultAllocator: Allocator<T, DimNameSum<Const<D>, U1>, DimNameSum<Const<D>, U1>>,
+{
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        self.matrix.fmt(formatter)
+    }
+}
+
 impl<T: RealField + hash::Hash, C: TCategory, const D: usize> hash::Hash for Transform<T, C, D>
 where
     Const<D>: DimNameAdd<U1>,
diff --git a/src/geometry/translation.rs b/src/geometry/translation.rs
index 8a64b97a..48656f9c 100755
--- a/src/geometry/translation.rs
+++ b/src/geometry/translation.rs
@@ -22,13 +22,18 @@ use crate::geometry::Point;
 
 /// A translation.
 #[repr(C)]
-#[derive(Debug)]
 pub struct Translation<T, const D: usize> {
     /// The translation coordinates, i.e., how much is added to a point's coordinates when it is
     /// translated.
     pub vector: SVector<T, D>,
 }
 
+impl<T: fmt::Debug, const D: usize> fmt::Debug for Translation<T, D> {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        self.vector.as_slice().fmt(formatter)
+    }
+}
+
 impl<T: Scalar + hash::Hash, const D: usize> hash::Hash for Translation<T, D>
 where
     Owned<T, Const<D>>: hash::Hash,
diff --git a/tests/core/matrix.rs b/tests/core/matrix.rs
index 4a35fb20..8a545e97 100644
--- a/tests/core/matrix.rs
+++ b/tests/core/matrix.rs
@@ -80,8 +80,8 @@ fn iter() {
 #[test]
 fn debug_output_corresponds_to_data_container() {
     let m = Matrix2::new(1.0, 2.0, 3.0, 4.0);
-    let output_stable = "Matrix { data: [[1, 3], [2, 4]] }"; // Current output on the stable channel.
-    let output_nightly = "Matrix { data: [[1.0, 3.0], [2.0, 4.0]] }"; // Current output on the nightly channel.
+    let output_stable = "[[1, 3], [2, 4]]"; // Current output on the stable channel.
+    let output_nightly = "[[1.0, 3.0], [2.0, 4.0]]"; // Current output on the nightly channel.
     let current_output = format!("{:?}", m);
     dbg!(output_stable);
     dbg!(output_nightly);