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authormatz <matz@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>1998-01-16 12:19:09 +0000
committermatz <matz@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>1998-01-16 12:19:09 +0000
commit62e41d3f2e48422bbdf1bb2db83ae60b255b1a1a (patch)
tree4d0edb1c1986e1578b181ebe2441acfee27f1fab /lib/weakref.rb
parent3db12e8b236ac8f88db8eb4690d10e4a3b8dbcd4 (diff)
Initial revision
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@8 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'lib/weakref.rb')
-rw-r--r--lib/weakref.rb70
1 files changed, 70 insertions, 0 deletions
diff --git a/lib/weakref.rb b/lib/weakref.rb
new file mode 100644
index 0000000..93b2c65
--- /dev/null
+++ b/lib/weakref.rb
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+# Weak Reference class that does not bother GCing.
+#
+# Usage:
+# foo = Object.new
+# foo.hash
+# foo = WeakRef.new(foo)
+# foo.hash
+# ObjectSpace.garbage_collect
+# foo.hash # => Raises WeakRef::RefError (because original GC'ed)
+
+require "delegate"
+
+class WeakRef<Delegater
+
+ Exception :RefError
+
+ ID_MAP = {}
+ ID_REV_MAP = {}
+ ObjectSpace.add_finalizer(lambda{|id|
+ rid = ID_MAP[id]
+ if rid
+ ID_REV_MAP[rid] = nil
+ ID_MAP[id] = nil
+ end
+ rid = ID_REV_MAP[id]
+ if rid
+ ID_REV_MAP[id] = nil
+ ID_MAP[rid] = nil
+ end
+ })
+
+ def initialize(orig)
+ super
+ @id = orig.id
+ ObjectSpace.call_finalizer orig
+ ID_MAP[@id] = self.id
+ ID_REV_MAP[self.id] = @id
+ end
+
+ def __getobj__
+ unless ID_MAP[@id]
+ $@ = caller(1)
+ $! = RefError.new("Illegal Reference - probably recycled")
+ raise
+ end
+ ObjectSpace.id2ref(@id)
+# ObjectSpace.each_object do |obj|
+# return obj if obj.id == @id
+# end
+ end
+
+ def weakref_alive?
+ if ID_MAP[@id]
+ true
+ else
+ false
+ end
+ end
+
+ def []
+ __getobj__
+ end
+end
+
+foo = Object.new
+p foo.hash
+foo = WeakRef.new(foo)
+p foo.hash
+ObjectSpace.garbage_collect
+p foo.hash