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AS guide: documents Object#presence

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1 parent 2e59151 commit 7f8d2cdb1715ddfaa27eed892df7ca9884e5315a @fxn fxn committed Dec 30, 2009
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  1. +8 −0 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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