yami.rb

tp = TracePoint.new(:call) do |tp|
  next unless tp.method_id == :===
  $v = tp.self
end
tp.enable

class C
  def deconstruct_keys(keys)
    result = {}
    result[:k] = $v
    result
  end
end

class Hoge
  class << self
    def ===(other)
      true
    end
  end
end

class Fuga
  class << self
    def ===(other)
      true
    end
  end
end

c = C.new

case c
in Hoge(k: v)
  puts v
end

case c
in Fuga(k: v)
  puts v
end

# yami.rb:33: warning: Pattern matching is experimental, and the behavior may change in future versions of Ruby!
# yami.rb:38: warning: Pattern matching is experimental, and the behavior may change in future versions of Ruby!
# Hoge
# Fuga