From dea0ccc1fd8c1e416ecd956141d1bf1bc030776f Mon Sep 17 00:00:00 2001
From: Jeroen Bollen <jbinero@gmail.com>
Date: Sun, 17 Apr 2016 09:23:37 +0200
Subject: [PATCH] Made PntAsVec use associated types. (#179)

Fix #177
---
 src/lib.rs                | 12 ++++++++----
 src/structs/pnt_macros.rs |  8 +++++---
 src/traits/structure.rs   | 22 +++++++++++++---------
 3 files changed, 26 insertions(+), 16 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index f6531611..bf3de13d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -311,9 +311,11 @@ pub fn orig<P: Orig>() -> P {
 
 /// Returns the center of two points.
 #[inline]
-pub fn center<N: BaseFloat, P: FloatPnt<N, V>, V: Copy + Norm<N>>(a: &P, b: &P) -> P {
+pub fn center<N: BaseFloat, P: FloatPnt<N>>(a: &P, b: &P) -> P
+        where <P as PntAsVec>::Vec: Norm<N>
+{
     let _2 = one::<N>() + one();
-    (*a + *b.as_vec()) / _2
+    (*a + b.to_vec()) / _2
 }
 
 /*
@@ -321,13 +323,15 @@ pub fn center<N: BaseFloat, P: FloatPnt<N, V>, V: Copy + Norm<N>>(a: &P, b: &P)
  */
 /// Returns the distance between two points.
 #[inline(always)]
-pub fn dist<N: BaseFloat, P: FloatPnt<N, V>, V: Norm<N>>(a: &P, b: &P) -> N {
+pub fn dist<N: BaseFloat, P: FloatPnt<N>>(a: &P, b: &P) -> N where <P as PntAsVec>::Vec: Norm<N> {
     a.dist(b)
 }
 
 /// Returns the squared distance between two points.
 #[inline(always)]
-pub fn sqdist<N: BaseFloat, P: FloatPnt<N, V>, V: Norm<N>>(a: &P, b: &P) -> N {
+pub fn sqdist<N: BaseFloat, P: FloatPnt<N>>(a: &P, b: &P) -> N 
+        where <P as PntAsVec>::Vec: Norm<N>
+{
     a.sqdist(b)
 }
 
diff --git a/src/structs/pnt_macros.rs b/src/structs/pnt_macros.rs
index 8b793b15..f5df77a9 100644
--- a/src/structs/pnt_macros.rs
+++ b/src/structs/pnt_macros.rs
@@ -82,7 +82,9 @@ macro_rules! pnt_as_vec_impl(
             }
         }
 
-        impl<N> PntAsVec<$tv<N>> for $t<N> {
+        impl<N> PntAsVec for $t<N> {
+            type Vec = $tv<N>;
+            
             #[inline]
             fn to_vec(self) -> $tv<N> {
                 self.to_vec()
@@ -132,11 +134,11 @@ macro_rules! pnt_from_homogeneous_impl(
 
 macro_rules! num_float_pnt_impl(
     ($t: ident, $tv: ident) => (
-        impl<N> NumPnt<N, $tv<N>> for $t<N>
+        impl<N> NumPnt<N> for $t<N>
             where N: BaseNum {
         }
 
-        impl<N> FloatPnt<N, $tv<N>> for $t<N>
+        impl<N> FloatPnt<N> for $t<N>
             where N: BaseFloat + ApproxEq<N> {
         }
     )
diff --git a/src/traits/structure.rs b/src/traits/structure.rs
index 28d49fc0..468c0258 100644
--- a/src/traits/structure.rs
+++ b/src/traits/structure.rs
@@ -236,38 +236,42 @@ pub trait FloatVec<N: BaseFloat>: NumVec<N> + Norm<N> + Neg<Output = Self> + Bas
  * Pnt related traits.
  */
 /// Trait that relates a point of an affine space to a vector of the associated vector space.
-pub trait PntAsVec<V> {
+pub trait PntAsVec {
+    /// The vector type of the vector space associated to this point's affine space.
+    type Vec;
+    
     /// Converts this point to its associated vector.
-    fn to_vec(self) -> V;
+    fn to_vec(self) -> Self::Vec;
 
     /// Converts a reference to this point to a reference to its associated vector.
-    fn as_vec<'a>(&'a self) -> &'a V;
+    fn as_vec<'a>(&'a self) -> &'a Self::Vec;
 
     // NOTE: this is used in some places to overcome some limitations untill the trait reform is
     // done on rustc.
     /// Sets the coordinates of this point to match those of a given vector.
-    fn set_coords(&mut self, coords: V);
+    fn set_coords(&mut self, coords: Self::Vec);
 }
 
 /// Trait grouping most common operations on points.
 // XXX: the vector space element `V` should be an associated type. Though this would prevent V from
 // having bounds (they are not supported yet). So, for now, we will just use a type parameter.
-pub trait NumPnt<N, V>:
+pub trait NumPnt<N>:
           Copy +
-          PntAsVec<V> +
+          PntAsVec +
           Dim +
           Orig +
           PartialEq +
           Axpy<N> +
-          Sub<Self, Output = V> +
+          Sub<Self, Output = <Self as PntAsVec>::Vec> +
           Mul<N, Output = Self> +
           Div<N, Output = Self> +
-          Add<V, Output = Self> +
+          Add<<Self as PntAsVec>::Vec, Output = Self> +
           Index<usize, Output = N> { // FIXME: + Sub<V, Self>
 }
 
 /// Trait of points with components implementing the `BaseFloat` trait.
-pub trait FloatPnt<N: BaseFloat, V: Norm<N>>: NumPnt<N, V> + Sized {
+pub trait FloatPnt<N: BaseFloat>: NumPnt<N> + Sized
+where <Self as PntAsVec>::Vec: Norm<N> {
     /// Computes the square distance between two points.
     #[inline]
     fn sqdist(&self, other: &Self) -> N {