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havenwood/tags.rb

Created November 15, 2025 19:34
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An example of ObjectSpace::WeakKeyMap, which was introduced in Ruby 3.3
Raw
tags.rb
require 'delegate'
class Tags < SimpleDelegator
def initialize = super(ObjectSpace::WeakKeyMap.new)
def tagged?(key) = key?(key)
end
TAGS = Tags.new
lamb = -> {}
TAGS[lamb] = :a_tag
TAGS.tagged?(lamb) #=> true
lamb = nil
TAGS.tagged?(lamb) #=> false
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