dynamical_class_define.rb

module Hoge
  class ArrayBase
    class << self
      attr_accessor :type
    end

    def type
      self.class.type
    end

    def initialize(values = [])
      @values = values.map { |v| type.new(v) }
    end

    def values
      @values
    end

    def values=(new_values)
      new_values.map { |v| type.new(v) }
    end
  end

  def Array(type)
    klass = Class.new(Hoge::ArrayBase)
    klass.type = type
    klass
  end

  module_function :Array

  class Foo
    attr_reader :value

    def initialize(value)
      @value = value
    end

    def to_s
      "Foo(v=#{value})"
    end
  end

  class Bar
    attr_reader :value

    def initialize(value)
      @value = value
    end

    def to_s
      "Bar(v=#{value})"
    end
  end
end

puts Hoge::Array(Hoge::Foo).new(%w(1 2 3)).values
puts Hoge::Array(Hoge::Bar).new(%w(1 2 3)).values

$ ruby  dynamical_class_define.rb
Foo(v=1)
Foo(v=2)
Foo(v=3)
Bar(v=1)
Bar(v=2)
Bar(v=3)

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