e.g. `object = Lazy.new(function: -> (id) { somethingThatFetch(id) }, value: 123)`. then `variable.anything` will load up the object

lazy.rb

class Lazy
  attr_reader :value

  def initialize(function:, value:)
    @function = function
    @value = value
    @cached = nil
    @is_cached = false
  end

  def hash
    value.hash
  end

  def eql?(other)
    if other.is_a?(Lazy)
      value == other.value
    else
      value == other
    end
  end

  def <=>(other)
    if other.is_a?(Lazy)
      value <=> other.value
    else
      value <=> other
    end
  end

  def method_missing(method, *args, &block)
    cached.send(method, *args, &block)
  end

  def cached
    unless @cached
      @cached = @function.call(value)
      @is_cached = true
    end

    @cached
  end

  def cached?
    @is_cached
  end

  def to_s
    cached.to_s
  end

  def inspect
    "#<Lazy @value=#{value.inspect} cached?=#{cached?.inspect}>"
  end
end