From f6116eb63e30538ae59081103fa3886f3a824688 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Mon, 12 Dec 2016 17:06:04 +1100
Subject: [PATCH] point: prefer constexpr functions over static variables

---
 point.cpp  |  4 ----
 point.hpp  |  2 +-
 point.ipp  | 23 +++++++++++++++++------
 region.cpp |  2 +-
 4 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/point.cpp b/point.cpp
index 5a9e62b1..fc1bef83 100644
--- a/point.cpp
+++ b/point.cpp
@@ -62,10 +62,6 @@ namespace util::debug  {
 }
 
 
-//-----------------------------------------------------------------------------
-template <size_t S, typename T>
-const util::point<S,T> util::point<S,T>::ORIGIN (T {0});
-
 //-----------------------------------------------------------------------------
 #define INSTANTIATE_S_T(S,T)        \
 template struct util::point<S,T>;   \
diff --git a/point.hpp b/point.hpp
index 8b40a5b3..c9bf480c 100644
--- a/point.hpp
+++ b/point.hpp
@@ -34,7 +34,7 @@ namespace util {
 
         template <size_t D> point<D,T> homog (void) const;
 
-        static const point<S,T> ORIGIN;
+        static constexpr point<S,T> origin (void);
 
         void sanity (void) const;
     };
diff --git a/point.ipp b/point.ipp
index 38b146f3..2635686b 100644
--- a/point.ipp
+++ b/point.ipp
@@ -18,7 +18,8 @@
 
 #include <algorithm>
 
-///------------------------------------------------------------------------
+
+///////////////////////////////////////////////////////////////////////////////
 /// expand point to use homogenous coordinates of a higher dimension.
 /// ie, fill with (0,..,0,1)
 template <size_t S, typename T>
@@ -45,7 +46,17 @@ util::point<S,T>::homog (void) const
 }
 
 
-//-------------------------------------------------------------------------
+///////////////////////////////////////////////////////////////////////////////
+template <size_t S, typename T>
+constexpr
+util::point<S,T>
+util::point<S,T>::origin (void)
+{
+    return point<S,T> {0};
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
 template <size_t S, typename T, typename U>
 typename std::common_type<T,U>::type
 util::distance (point<S,T> a, point<S,U> b)
@@ -58,7 +69,7 @@ util::distance (point<S,T> a, point<S,U> b)
 }
 
 
-//-------------------------------------------------------------------------
+///////////////////////////////////////////////////////////////////////////////
 template <size_t S, typename T, typename U>
 constexpr typename std::common_type<T,U>::type
 util::distance2 (point<S,T> a, point<S,U> b)
@@ -72,7 +83,7 @@ util::distance2 (point<S,T> a, point<S,U> b)
 }
 
 
-//-------------------------------------------------------------------------
+///////////////////////////////////////////////////////////////////////////////
 template <typename T, typename U>
 typename std::common_type<T,U>::type
 util::octile (point2<T> a, point2<U> b)
@@ -96,7 +107,7 @@ util::octile (point2<T> a, point2<U> b)
 }
 
 
-//-------------------------------------------------------------------------
+///////////////////////////////////////////////////////////////////////////////
 template <size_t S, typename T, typename U>
 constexpr typename std::common_type<T,U>::type
 util::manhattan (point<S,T> a, point<S,U> b)
@@ -110,7 +121,7 @@ util::manhattan (point<S,T> a, point<S,U> b)
 }
 
 
-//-------------------------------------------------------------------------
+///////////////////////////////////////////////////////////////////////////////
 template <size_t S, typename T, typename U>
 constexpr typename std::common_type<T,U>::type
 util::chebyshev(point<S,T> a, point<S,U> b)
diff --git a/region.cpp b/region.cpp
index bcc8f950..0203010d 100644
--- a/region.cpp
+++ b/region.cpp
@@ -25,7 +25,7 @@
 //-----------------------------------------------------------------------------
 template <size_t S, typename T>
 util::region<S,T>::region (extent_t _extent):
-    region (point_t::ORIGIN, _extent)
+    region (point_t::origin (), _extent)
 {
     debug::sanity (*this);
 }