From 4bf160934c2a093c5010b97c296c0cd3322698e9 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Mon, 12 Dec 2016 17:04:22 +1100
Subject: [PATCH] vector: prefer constexpr functions over static variables

---
 test/coord.cpp  |  2 +-
 test/vector.cpp |  4 ++--
 vector.cpp      | 12 ------------
 vector.hpp      |  4 ++--
 vector.ipp      | 20 ++++++++++++++++++++
 5 files changed, 25 insertions(+), 17 deletions(-)

diff --git a/test/coord.cpp b/test/coord.cpp
index 1b7c7b70..255017c1 100644
--- a/test/coord.cpp
+++ b/test/coord.cpp
@@ -34,7 +34,7 @@ main (void)
     auto vec = util::vector4f (0.5f);
     t.expect_eq (vec, util::normalised (vec), "normalisation of normalised vector");
 
-    t.expect_eq (sum (util::vector4f::ONES), 4.f, "elementwise summation");
+    t.expect_eq (sum (util::vector4f::ones ()), 4.f, "elementwise summation");
 
     return t.status ();
 }
diff --git a/test/vector.cpp b/test/vector.cpp
index e1134f5e..394e48d9 100644
--- a/test/vector.cpp
+++ b/test/vector.cpp
@@ -111,8 +111,8 @@ main ()
     test_polar (tap);
     test_euler (tap);
 
-    tap.expect (!is_normalised (util::vector3f::ZERO), "zero isn't normalised");
-    tap.expect (!is_normalised (util::vector3f::ONES), "ones isn't normalised");
+    tap.expect (!is_normalised (util::vector3f::zeros ()), "zeros isn't normalised");
+    tap.expect (!is_normalised (util::vector3f::ones  ()), "ones isn't normalised");
 
     tap.expect_eq (
         util::hypot (util::vector3f{0,1,2} - util::vector3f{3,2,4}),
diff --git a/vector.cpp b/vector.cpp
index 8ee61a3d..da76eced 100644
--- a/vector.cpp
+++ b/vector.cpp
@@ -112,18 +112,6 @@ util::cartesian_to_spherical (vector<3,T> c)
 }
 
 
-///////////////////////////////////////////////////////////////////////////////
-template <size_t S, typename T>
-const util::vector<S,T>
-util::vector<S,T>::ONES (T{1});
-
-
-//-----------------------------------------------------------------------------
-template <size_t S, typename T>
-const util::vector<S,T>
-util::vector<S,T>::ZERO (T{0});
-
-
 ///////////////////////////////////////////////////////////////////////////////
 template <size_t S, typename T>
 void
diff --git a/vector.hpp b/vector.hpp
index 4f34b6d9..72c511ed 100644
--- a/vector.hpp
+++ b/vector.hpp
@@ -30,8 +30,8 @@ namespace util {
         template <size_t D> vector<D,T> homog (void) const;
 
         // constants
-        static const vector<S,T> ONES;
-        static const vector<S,T> ZERO;
+        static constexpr vector<S,T> ones  (void);
+        static constexpr vector<S,T> zeros (void);
 
         void sanity (void) const;
     };
diff --git a/vector.ipp b/vector.ipp
index 6e4750fe..83e8fab3 100644
--- a/vector.ipp
+++ b/vector.ipp
@@ -46,3 +46,23 @@ util::cross (util::vector<3,T> a, util::vector<3,T> b)
         a.x * b.y - a.y * b.x
     };
 }
+
+
+///////////////////////////////////////////////////////////////////////////////
+template <size_t S, typename T>
+constexpr
+util::vector<S,T>
+util::vector<S,T>::ones (void)
+{
+    return vector<S,T> {1};
+}
+
+
+//-----------------------------------------------------------------------------
+template <size_t S, typename T>
+constexpr
+util::vector<S,T>
+util::vector<S,T>::zeros (void)
+{
+    return vector<S,T> {0};
+}