From acedac53d0b168b9279849abef80eaf7ee467f10 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Thu, 7 Sep 2017 12:49:58 +1000
Subject: [PATCH] except: automatically detect ValueT for try_value

---
 except.hpp | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/except.hpp b/except.hpp
index 3b8769e..f0272d5 100644
--- a/except.hpp
+++ b/except.hpp
@@ -64,13 +64,20 @@ namespace cruft::vk {
         }
 
 
-        /// requests a ValueT using a invokable FuncT with arguments
+        /// returns a ValueT using an invokable FuncT with arguments
         /// [Args..., &ValueT] and returns the result after testing for
         /// success.
-        template <typename ValueT, typename FuncT, typename ...Args>
-        static ValueT
+        template <typename FuncT, typename ...Args>
+        static auto
         try_query (FuncT &&func, Args &&...args)
         {
+            using ValueT = std::remove_pointer_t<
+                std::tuple_element_t<
+                    sizeof... (Args),
+                    typename func_traits<FuncT>::argument_types
+                >
+            >;
+
             ValueT value;
             try_func (func, std::forward<Args> (args)..., &value);
             return value;