added len function to Array

src/point.rs

@@ -103,6 +103,11 @@ macro_rules! impl_point {
         impl<S: BaseNum> Array for $PointN<S> {
             type Element = S;
 
+            #[inline]
+            fn len() -> usize {
+                $n
+            }
+
             #[inline]
             fn from_value(scalar: S) -> $PointN<S> {
                 $PointN { $($field: scalar),+ }

src/structure.rs

@@ -35,6 +35,16 @@ pub trait Array where
 {
     type Element: Copy;
 
+    /// Get the number of elements in the array type
+    ///
+    /// ```rust
+    /// use cgmath::prelude::*;
+    /// use cgmath::Vector3;
+    ///
+    /// assert_eq!(Vector3::<f32>::len(), 3);
+    /// ```
+    fn len() -> usize;
+
     /// Construct a vector from a single value, replicating it.
     ///
     /// ```rust

src/vector.rs

@@ -129,6 +129,11 @@ macro_rules! impl_vector {
         impl<S: Copy> Array for $VectorN<S> {
             type Element = S;
 
+            #[inline]
+            fn len() -> usize {
+                $n
+            }
+
             #[inline]
             fn from_value(scalar: S) -> $VectorN<S> {
                 $VectorN { $($field: scalar),+ }