From fd949663d2229419a1e53e69351205cd27157653 Mon Sep 17 00:00:00 2001
From: Yukihiro Matsumoto <matz@ruby-lang.org>
Date: Fri, 19 Oct 2012 21:09:34 +0900
Subject: Enumerable#inject should handle empty enumerable;
 http://www.tbn.co.jp/blog/?p=813

---
 mrblib/enum.rb | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/mrblib/enum.rb b/mrblib/enum.rb
index 2699a18af..666ada294 100644
--- a/mrblib/enum.rb
+++ b/mrblib/enum.rb
@@ -200,13 +200,18 @@ module Enumerable
   # ISO 15.3.2.2.11
   def inject(*args, &block)
     raise ArgumentError, "too many arguments" if args.size > 2
-    flag = true  # 1st element?
-    result = nil
+    if args.empty?
+      flag = true  # no initial argument
+      result = nil
+    else
+      flag = false
+      result = args[0]
+    end
     self.each{|val|
       if flag
-        # 1st element
-        result = (args.empty?)? val: block.call(args[0], val)
+        # push first element as initial
         flag = false
+        result = val
       else
         result = block.call(result, val)
       end
-- 
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