From 3f842c733568aa9068aa83fad52540eb98f334b1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Wed, 20 Jul 2022 20:25:59 +0200
Subject: Simplify require, prefer.

---
 c/common.h | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

(limited to 'c/common.h')

diff --git a/c/common.h b/c/common.h
index 24c98c8..01083b8 100644
--- a/c/common.h
+++ b/c/common.h
@@ -55,24 +55,23 @@ std::optional<T> maybe_make(U... xs)
 }
 
 /* Call Windows API function, throwing error on NULL. */
-template <auto F, typename... T>
-inline auto require(T... xs)
+template <typename T>
+inline T require(T x)
 {
-	if (auto r = F(xs...)) return r;
-	else throw Win32Error();
+	if (!x) throw Win32Error();
+	return x;
 }
 
 /* Call Windows API function, showing a warning on NULL. */
-template <auto F, typename... T>
-inline auto prefer(T... xs)
+template <typename T>
+inline T prefer(T x)
 {
-	if (auto r = F(xs...))
-		return r;
-	else {
+	if (!x) {
 		EBMessageBox(Win32Error().what<TCHAR>(),
-			TEXT("System Error"), MB_ICONWARNING);
-		return (decltype(F(std::declval<T>()...)))NULL;
+		    TEXT("System Error"), MB_ICONWARNING);
+		return (T)NULL;
 	}
+	return x;
 }
 
 /* Return integer scaled for current DPI. */
-- 
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