Class: WeakRef

WeakRef is a class to represent a reference to an object that is not seen by the tracing phase of the garbage collector. This allows the referenced object to be garbage collected as if nothing is referring to it. Because WeakRef delegates method calls to the referenced object, it may be used in place of that object, i.e. it is of the same duck type.

Usage:

  foo = Object.new
  foo = Object.new
  p foo.to_s                  # original's class
  foo = WeakRef.new(foo)
  p foo.to_s                  # should be same class
  ObjectSpace.garbage_collect
  p foo.to_s                  # should raise exception (recycled)

Methods

__getobj__ __setobj__ new weakref_alive?

Classes and Modules

Class WeakRef::RefError

Public Class methods

new(orig)

Create a new WeakRef from orig.

[Source]

# File weakref.rb, line 49
  def initialize(orig)
    super
    __setobj__(orig)
  end

Public Instance methods

__getobj__()

Return the object this WeakRef references. Raises RefError if the object has been garbage collected. The object returned is the object to which method calls are delegated (see Delegator).

[Source]

# File weakref.rb, line 57
  def __getobj__
    unless @@id_rev_map[self.__id__] == @__id
      raise RefError, "Illegal Reference - probably recycled", caller(2)
    end
    begin
      ObjectSpace._id2ref(@__id)
    rescue RangeError
      raise RefError, "Illegal Reference - probably recycled", caller(2)
    end
  end

__setobj__(obj)

[Source]

# File weakref.rb, line 68
  def __setobj__(obj)
    @__id = obj.__id__
    __old_status = Thread.critical
    begin
      Thread.critical = true
      unless @@id_rev_map.key?(self)
        ObjectSpace.define_finalizer obj, @@final
        ObjectSpace.define_finalizer self, @@final
      end
      @@id_map[@__id] = [] unless @@id_map[@__id]
    ensure
      Thread.critical = __old_status
    end
    @@id_map[@__id].push self.__id__
    @@id_rev_map[self.__id__] = @__id
  end

weakref_alive?()

Returns true if the referenced object still exists, and false if it has been garbage collected.

[Source]

# File weakref.rb, line 87
  def weakref_alive?
    @@id_rev_map[self.__id__] == @__id
  end

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