From cb7bd4d1f216d8176a200ac99863725bc9f08fa2 Mon Sep 17 00:00:00 2001
From: Roland Conybeare <rconybeare@gmail.com>
Date: Sat, 4 May 2024 11:37:24 -0400
Subject: [PATCH] xo-unit: + quantity methods .is_dimensionless(), arith
 conversion

---
 include/xo/unit/quantity.hpp | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/include/xo/unit/quantity.hpp b/include/xo/unit/quantity.hpp
index 2eff0adf..87f7b4ac 100644
--- a/include/xo/unit/quantity.hpp
+++ b/include/xo/unit/quantity.hpp
@@ -37,7 +37,9 @@ namespace xo {
             constexpr const repr_type & scale() const { return scale_; }
             constexpr const unit_type & unit() const { return s_unit; }
 
-            // is_dimensionless
+            constexpr bool is_dimensionless() const {
+                return s_unit.is_dimensionless();
+            }
 
             // unit_qty
             // zero_qty
@@ -152,6 +154,12 @@ namespace xo {
                 return this->template rescale<Q2::s_unit>().template with_repr<typename Q2::repr_type>();
             }
 
+            constexpr operator Repr() const
+                requires (NaturalUnit.is_dimensionless())
+                {
+                    return scale_;
+                }
+
         public: /* need public members so that a quantity instance can be a non-type template parameter (is a structural type) */
             static constexpr natural_unit<ratio_int_type> s_unit = NaturalUnit;