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module Universa
# The smarter and safer weak reference than a standard one.
# It keeps object_id even if it is GC'd and can create a hard
# reference when possible. Some code borrowed from
# https://github.com/ruby-concurrency/ref.
#
# Note there is no +alive?+ method because it is not thread safe.
# Use the safe approach:
#
# weak = WeakReference.new(something)
# hard = weak.get
# if hard
# # we got safe reference in +hard+
# end
#
# or, scala/kotlin-style:
#
# weak.let { |object|
# object.do_somethinf
# }
#
class WeakReference
# ruby object it of the referenced object. Available also after object is recycled.
attr :referenced_object_id
# Create weak reference for a given object
def initialize(object)
@referenced_object_id = object.__id__
@weakref = WeakRef.new(object)
end
# Call the block passing it hard ref to the object if it is not yet recycled
#
# @return what the block returned or nil
# @yield object if it is not recycled
def let
if (hardref = object.get)
yield hardref
else
nil
end
end
# Get the strong reference unless it is already reclaimed.
#
# @return [Object] har reference to the source object or nil
def get
@weakref.__getobj__
rescue => e
# Jruby implementation uses RefError while MRI uses WeakRef::RefError
if (defined?(RefError) && e.is_a?(RefError)) || (defined?(::WeakRef::RefError) && e.is_a?(::WeakRef::RefError))
nil
else
raise e
end
end
end
end
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50 entries across 50 versions & 1 rubygems