From 7b6123f6a60e0d041aa7673c6077a254656c6c08 Mon Sep 17 00:00:00 2001
From: jmdavis <jmdavisProg@gmx.com>
Date: Sat, 21 Jun 2014 21:30:11 -0700
Subject: [PATCH] Slight improvement to enforceEx's constraints and its
 documentation.

---
 std/exception.d | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/std/exception.d b/std/exception.d
index 2908b9c80..382ea7ed3 100644
--- a/std/exception.d
+++ b/std/exception.d
@@ -520,9 +520,10 @@ T errnoEnforce(T, string file = __FILE__, size_t line = __LINE__)
     enforceEx!DataCorruptionException(line.length);
     --------------------
  +/
-template enforceEx(E)
+template enforceEx(E : Throwable)
     if (is(typeof(new E("", __FILE__, __LINE__))))
 {
+    /++ Ditto +/
     T enforceEx(T)(T value, lazy string msg = "", string file = __FILE__, size_t line = __LINE__)
     {
         if (!value) throw new E(msg, file, line);
@@ -530,9 +531,11 @@ template enforceEx(E)
     }
 }
 
-template enforceEx(E)
+/++ Ditto +/
+template enforceEx(E : Throwable)
     if (is(typeof(new E(__FILE__, __LINE__))) && !is(typeof(new E("", __FILE__, __LINE__))))
 {
+    /++ Ditto +/
     T enforceEx(T)(T value, string file = __FILE__, size_t line = __LINE__)
     {
         if (!value) throw new E(file, line);
@@ -561,6 +564,24 @@ unittest
         assert(e.file == "file");
         assert(e.line == 42);
     }
+
+    {
+        auto e = collectException!Error(enforceEx!OutOfMemoryError(false));
+        assert(e !is null);
+        assert(e.msg == "Memory allocation failed");
+        assert(e.file == __FILE__);
+        assert(e.line == __LINE__ - 4);
+    }
+
+    {
+        auto e = collectException!Error(enforceEx!OutOfMemoryError(false, "file", 42));
+        assert(e !is null);
+        assert(e.msg == "Memory allocation failed");
+        assert(e.file == "file");
+        assert(e.line == 42);
+    }
+
+    static assert(!is(typeof(enforceEx!int(true))));
 }
 
 unittest