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c8a7361e45
and Marshal::MINOR_VERSION. * marshal.c (marshal_load): ruby_verbose test should be wrapped by RTEST(). * hash.c (rb_hash_index): should return nil (not the default value) if value is not in the hash. * numeric.c (num_div): new method added. alias to '/' which should be preserved even if '/' is redefined (e.g. by mathn). [new] * bignum.c (rb_cstr2inum): "0 ff".hex should return 0, not 255. * file.c (rb_file_s_expand_path): fixed using CharNext(). git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@1658 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
49 lines
1 KiB
Ruby
49 lines
1 KiB
Ruby
# Singleton module that ensures only one object to be allocated.
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#
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# Usage:
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# class SomeSingletonClass
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# include Singleton
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# #....
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# end
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# a = SomeSingletonClass.instance
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# b = SomeSingletonClass.instance # a and b are same object
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# p [a,b]
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# a = SomeSingletonClass.new # error (`new' is private)
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module Singleton
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def Singleton.included(klass)
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klass.private_class_method(:new)
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klass.instance_eval %{
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@__instance__ = nil
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def instance
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if defined? @__allocating__
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until @__instance__
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sleep 0.5
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end
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elsif ! @__instance__
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Thread.critical = true
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@__allocating__ = true
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Thread.critical = false
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begin
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@__instance__ = new
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ensure
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remove_instance_variable(:@__allocating__)
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end
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end
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return @__instance__
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end
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}
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end
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end
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if __FILE__ == $0
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class SomeSingletonClass
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include Singleton
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#....
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end
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a = SomeSingletonClass.instance
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b = SomeSingletonClass.instance # a and b are same object
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p [a,b]
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a = SomeSingletonClass.new # error (`new' is private)
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end
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