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ruby--ruby/lib/weakref.rb
marcandre 013dcf08a1 lib/weakref: Remove incorrect example [DOC] [Bug ]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60404 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
2017-10-24 18:08:00 +00:00

60 lines
1.4 KiB
Ruby

# frozen_string_literal: true
require "delegate"
# Weak Reference class that allows a referenced object to be
# garbage-collected.
#
# A WeakRef may be used exactly like the object it references.
#
# Usage:
#
# foo = Object.new # create a new object instance
# p foo.to_s # original's class
# foo = WeakRef.new(foo) # reassign foo with WeakRef instance
# p foo.to_s # should be same class
# GC.start # start the garbage collector
# p foo.to_s # should raise exception (recycled)
#
class WeakRef < Delegator
##
# RefError is raised when a referenced object has been recycled by the
# garbage collector
class RefError < StandardError
end
@@__map = ::ObjectSpace::WeakMap.new
##
# Creates a weak reference to +orig+
#
# Raises an ArgumentError if the given +orig+ is immutable, such as Symbol,
# Integer, or Float.
def initialize(orig)
case orig
when true, false, nil
@delegate_sd_obj = orig
else
@@__map[self] = orig
end
super
end
def __getobj__ # :nodoc:
@@__map[self] or defined?(@delegate_sd_obj) ? @delegate_sd_obj :
Kernel::raise(RefError, "Invalid Reference - probably recycled", Kernel::caller(2))
end
def __setobj__(obj) # :nodoc:
end
##
# Returns true if the referenced object is still alive.
def weakref_alive?
@@__map.key?(self) or defined?(@delegate_sd_obj)
end
end