From 7f8d2cdb1715ddfaa27eed892df7ca9884e5315a Mon Sep 17 00:00:00 2001
From: Xavier Noria <fxn@hashref.com>
Date: Wed, 30 Dec 2009 22:53:44 +0100
Subject: [PATCH] AS guide: documents Object#presence

---
 .../guides/source/active_support_core_extensions.textile  | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/railties/guides/source/active_support_core_extensions.textile b/railties/guides/source/active_support_core_extensions.textile
index 8ba283122d..0e4f1da7b2 100644
--- a/railties/guides/source/active_support_core_extensions.textile
+++ b/railties/guides/source/active_support_core_extensions.textile
@@ -48,6 +48,14 @@ The method +present?+ is equivalent to +!blank?+:
 assert @response.body.present? # same as !@response.body.blank?
 </ruby>
 
+h4. +presence+
+
+The +presence+ method returns its receiver if +present?+, and +nil+ otherwise. It is useful for idioms like this:
+
+<ruby>
+host = config[:host].presence || 'localhost'
+</ruby>
+
 h4. +duplicable?+
 
 A few fundamental objects in Ruby are singletons. For example, in the whole live of a program the integer 1 refers always to the same instance:
-- 
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