GIF87a;
require 'thread' # The Singleton module implements the Singleton pattern. # # == Usage # # To use Singleton, include the module in your class. # # class Klass # include Singleton # # ... # end # # This ensures that only one instance of Klass can be created. # # a,b = Klass.instance, Klass.instance # # a == b # # => true # # Klass.new # # => NoMethodError - new is private ... # # The instance is created at upon the first call of Klass.instance(). # # class OtherKlass # include Singleton # # ... # end # # ObjectSpace.each_object(OtherKlass){} # # => 0 # # OtherKlass.instance # ObjectSpace.each_object(OtherKlass){} # # => 1 # # # This behavior is preserved under inheritance and cloning. # # == Implementation # # This above is achieved by: # # * Making Klass.new and Klass.allocate private. # # * Overriding Klass.inherited(sub_klass) and Klass.clone() to ensure that the # Singleton properties are kept when inherited and cloned. # # * Providing the Klass.instance() method that returns the same object each # time it is called. # # * Overriding Klass._load(str) to call Klass.instance(). # # * Overriding Klass#clone and Klass#dup to raise TypeErrors to prevent # cloning or duping. # # == Singleton and Marshal # # By default Singleton's #_dump(depth) returns the empty string. Marshalling by # default will strip state information, e.g. instance variables and taint # state, from the instance. Classes using Singleton can provide custom # _load(str) and _dump(depth) methods to retain some of the previous state of # the instance. # # require 'singleton' # # class Example # include Singleton # attr_accessor :keep, :strip # def _dump(depth) # # this strips the @strip information from the instance # Marshal.dump(@keep, depth) # end # # def self._load(str) # instance.keep = Marshal.load(str) # instance # end # end # # a = Example.instance # a.keep = "keep this" # a.strip = "get rid of this" # a.taint # # stored_state = Marshal.dump(a) # # a.keep = nil # a.strip = nil # b = Marshal.load(stored_state) # p a == b # => true # p a.keep # => "keep this" # p a.strip # => nil # module Singleton # Raises a TypeError to prevent cloning. def clone raise TypeError, "can't clone instance of singleton #{self.class}" end # Raises a TypeError to prevent duping. def dup raise TypeError, "can't dup instance of singleton #{self.class}" end # By default, do not retain any state when marshalling. def _dump(depth = -1) '' end module SingletonClassMethods # :nodoc: def clone # :nodoc: Singleton.__init__(super) end # By default calls instance(). Override to retain singleton state. def _load(str) instance end private def inherited(sub_klass) super Singleton.__init__(sub_klass) end end class << Singleton # :nodoc: def __init__(klass) # :nodoc: klass.instance_eval { @singleton__instance__ = nil @singleton__mutex__ = Mutex.new } def klass.instance # :nodoc: return @singleton__instance__ if @singleton__instance__ @singleton__mutex__.synchronize { return @singleton__instance__ if @singleton__instance__ @singleton__instance__ = new() } @singleton__instance__ end klass end private # extending an object with Singleton is a bad idea undef_method :extend_object def append_features(mod) # help out people counting on transitive mixins unless mod.instance_of?(Class) raise TypeError, "Inclusion of the OO-Singleton module in module #{mod}" end super end def included(klass) super klass.private_class_method :new, :allocate klass.extend SingletonClassMethods Singleton.__init__(klass) end end ## # :singleton-method: _load # By default calls instance(). Override to retain singleton state. end
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bigdecimal | Folder | 0755 |
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cgi | Folder | 0755 |
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date | Folder | 0755 |
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digest | Folder | 0755 |
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dl | Folder | 0755 |
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drb | Folder | 0755 |
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fiddle | Folder | 0755 |
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io | Folder | 0755 |
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irb | Folder | 0755 |
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json | Folder | 0755 |
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matrix | Folder | 0755 |
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net | Folder | 0755 |
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openssl | Folder | 0755 |
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optparse | Folder | 0755 |
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psych | Folder | 0755 |
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racc | Folder | 0755 |
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rbconfig | Folder | 0755 |
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rexml | Folder | 0755 |
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rinda | Folder | 0755 |
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ripper | Folder | 0755 |
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rss | Folder | 0755 |
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shell | Folder | 0755 |
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syslog | Folder | 0755 |
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test | Folder | 0755 |
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uri | Folder | 0755 |
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vendor_ruby | Folder | 0755 |
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webrick | Folder | 0755 |
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xmlrpc | Folder | 0755 |
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yaml | Folder | 0755 |
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English.rb | File | 6.44 KB | 0644 |
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abbrev.rb | File | 3.31 KB | 0644 |
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base64.rb | File | 2.63 KB | 0644 |
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benchmark.rb | File | 17.94 KB | 0644 |
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cgi.rb | File | 9.39 KB | 0644 |
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cmath.rb | File | 7.22 KB | 0644 |
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complex.rb | File | 380 B | 0644 |
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csv.rb | File | 81.32 KB | 0644 |
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date.rb | File | 946 B | 0644 |
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debug.rb | File | 28.9 KB | 0644 |
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delegate.rb | File | 9.78 KB | 0644 |
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digest.rb | File | 2.24 KB | 0644 |
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dl.rb | File | 280 B | 0644 |
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drb.rb | File | 19 B | 0644 |
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e2mmap.rb | File | 3.8 KB | 0644 |
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erb.rb | File | 26.08 KB | 0644 |
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expect.rb | File | 2.14 KB | 0644 |
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fiddle.rb | File | 1.25 KB | 0644 |
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fileutils.rb | File | 46.35 KB | 0644 |
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find.rb | File | 2.08 KB | 0644 |
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forwardable.rb | File | 7.56 KB | 0644 |
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getoptlong.rb | File | 15.38 KB | 0644 |
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gserver.rb | File | 8.86 KB | 0644 |
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ipaddr.rb | File | 26.17 KB | 0644 |
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irb.rb | File | 20.03 KB | 0644 |
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json.rb | File | 1.74 KB | 0644 |
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kconv.rb | File | 5.74 KB | 0644 |
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logger.rb | File | 20.96 KB | 0644 |
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mathn.rb | File | 6.52 KB | 0644 |
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matrix.rb | File | 45.02 KB | 0644 |
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mkmf.rb | File | 78.13 KB | 0644 |
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monitor.rb | File | 6.93 KB | 0644 |
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mutex_m.rb | File | 2 KB | 0644 |
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observer.rb | File | 5.71 KB | 0644 |
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open-uri.rb | File | 23.66 KB | 0644 |
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open3.rb | File | 21.17 KB | 0644 |
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openssl.rb | File | 528 B | 0644 |
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optparse.rb | File | 51.27 KB | 0644 |
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ostruct.rb | File | 7.64 KB | 0644 |
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pathname.rb | File | 15.3 KB | 0644 |
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pp.rb | File | 13.14 KB | 0644 |
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prettyprint.rb | File | 9.63 KB | 0644 |
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prime.rb | File | 13.98 KB | 0644 |
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profile.rb | File | 205 B | 0644 |
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profiler.rb | File | 4.29 KB | 0644 |
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pstore.rb | File | 14.85 KB | 0644 |
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psych.rb | File | 11.45 KB | 0644 |
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rational.rb | File | 308 B | 0644 |
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resolv-replace.rb | File | 1.73 KB | 0644 |
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resolv.rb | File | 61.46 KB | 0644 |
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ripper.rb | File | 2.53 KB | 0644 |
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rss.rb | File | 2.84 KB | 0644 |
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scanf.rb | File | 23.52 KB | 0644 |
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securerandom.rb | File | 8.56 KB | 0644 |
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set.rb | File | 17.32 KB | 0644 |
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shell.rb | File | 10.3 KB | 0644 |
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shellwords.rb | File | 5.94 KB | 0644 |
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singleton.rb | File | 4.02 KB | 0644 |
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socket.rb | File | 25.76 KB | 0644 |
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sync.rb | File | 7.26 KB | 0644 |
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tempfile.rb | File | 10.15 KB | 0644 |
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thread.rb | File | 6.94 KB | 0644 |
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thwait.rb | File | 3.38 KB | 0644 |
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time.rb | File | 21.09 KB | 0644 |
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timeout.rb | File | 3.16 KB | 0644 |
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tmpdir.rb | File | 4.29 KB | 0644 |
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tracer.rb | File | 6.54 KB | 0644 |
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tsort.rb | File | 6.79 KB | 0644 |
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un.rb | File | 8.34 KB | 0644 |
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uri.rb | File | 3.07 KB | 0644 |
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weakref.rb | File | 3.23 KB | 0644 |
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webrick.rb | File | 6.7 KB | 0644 |
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xmlrpc.rb | File | 8.49 KB | 0644 |
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yaml.rb | File | 2.3 KB | 0644 |
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