From 95ac869522496d0c9e4689f3066ae146187f5253 Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Sun, 27 Jun 2021 11:31:54 +0200
Subject: [PATCH] extended is_quantity<T> to support quantity-derived classes

N.B. inheritance is preferred to composition/delegate class to avoid duplication and also inherent the various required operators ('+','-',..., '+=', ...) for details see discussion #271
---
 src/core/include/units/bits/basic_concepts.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/core/include/units/bits/basic_concepts.h b/src/core/include/units/bits/basic_concepts.h
index 4ec56115..94425df1 100644
--- a/src/core/include/units/bits/basic_concepts.h
+++ b/src/core/include/units/bits/basic_concepts.h
@@ -269,7 +269,7 @@ concept Reference = detail::is_reference<T>;
 namespace detail {
 
 template<typename T>
-inline constexpr bool is_quantity = false;
+inline constexpr bool is_quantity = requires { typename T::dimension;  typename T::unit;  typename T::rep;};
 
 template<typename T>
 inline constexpr bool is_quantity_point = false;