gistfile1.rb

class LazEvalProxy

  alias_method :proxy_respond_to?, :respond_to?
  alias_method :proxy_extend, :extend
  instance_methods.each { |m| undef_method m unless m =~ /(^__|^proxy_)/ }
  attr_accessor :proxy_block, :proxy_object

  def initialize(object, block)
    @proxy_object, @proxy_block = object, block
  end

  def method_missing(*args, &block)
    unless defined?(@result)
      @result = proxy_object.instance_eval &proxy_block
    end
    @result.send(*args, &block)
  end

end

def Object.lazeval(&block)
  LazEvalProxy.new self, block
end

def lazeval(&block)
  LazEvalProxy.new self, block
end
# x = proc{|n| [n, lazeval{ x.call(n+1)  } ] } # will system_stack_error in irb