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object.duplicable? returns true if object.dup is safe. False for nil,…

… true, false, symbols, and numbers; true otherwise. References #9333.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@7906 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
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commit bb4ebaa858c3c73888ffb4639f6854b78955f9ed 1 parent fe234a1
@jeremy jeremy authored
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2  activesupport/CHANGELOG
@@ -1,5 +1,7 @@
*SVN*
+* object.duplicable? returns true if object.dup is safe. False for nil, true, false, symbols, and numbers; true otherwise. #9333 [sur]
+
* Time, Date and DateTime #advance accept :weeks option. #9866 [Geoff Buesing]
* Fix Time#years_ago and #years_since from leap days. #9865 [Geoff Buesing]
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37 activesupport/lib/active_support/core_ext/duplicable.rb
@@ -0,0 +1,37 @@
+class Object
+ # Can you safely .dup this object?
+ # False for nil, false, true, symbols, and numbers; true otherwise.
+ def duplicable?
+ true
+ end
+end
+
+class NilClass #:nodoc:
+ def duplicable?
+ false
+ end
+end
+
+class FalseClass #:nodoc:
+ def duplicable?
+ false
+ end
+end
+
+class TrueClass #:nodoc:
+ def duplicable?
+ false
+ end
+end
+
+class Symbol #:nodoc:
+ def duplicable?
+ false
+ end
+end
+
+class Numeric #:nodoc:
+ def duplicable?
+ false
+ end
+end
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22 activesupport/test/core_ext/duplicable_test.rb
@@ -0,0 +1,22 @@
+require File.dirname(__FILE__) + '/../abstract_unit'
+
+class DuplicableTest < Test::Unit::TestCase
+ NO = [nil, false, true, :symbol, 1, 2.3, BigDecimal.new('4.56')]
+ YES = ['1', Object.new, /foo/, [], {}]
+
+ def test_duplicable
+ NO.each do |v|
+ assert !v.duplicable?
+ begin
+ v.dup
+ fail
+ rescue Exception
+ end
+ end
+
+ YES.each do |v|
+ assert v.duplicable?
+ assert_nothing_raised { v.dup }
+ end
+ end
+end
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