rb-make-iseq-umethod.rb

require 'fiddle'

class RubyVM
  class InstructionSequence
    func = Fiddle::Function.new(Fiddle::Handle::DEFAULT['rb_iseq_load'], [Fiddle::TYPE_VOIDP] * 3, Fiddle::TYPE_VOIDP)
    define_singleton_method(:load) do |data, parent = nil, opt = nil|
      func.call(Fiddle.dlwrap(data), parent, opt).to_value
    end
  end
end

class C
  def default_iseq
    self
  end
  DEFAULT_ISEQ = RubyVM::InstructionSequence.of(instance_method(:default_iseq)).to_a.freeze

  def make_unbound_method(options = {})
    opts = {module_name: :Foo, method_name: :changeme, instructions: DEFAULT_ISEQ}.merge(options)
    module_name = opts[:module_name]
    method_name = opts[:method_name]
    instructions = opts[:instructions]
    RubyVM::InstructionSequence.load(Marshal.load(Marshal.dump(["YARVInstructionSequence/SimpleDataFormat", 2, 0, 1, {:arg_size=>0, :local_size=>2, :stack_max=>2}, "<compiled>", "", "", 0, :top, [:mod], 0, [], [[:putnil], [:getconstant, :Module], [:send, {:mid=>:new, :flag=>256, :orig_argc=>0, :blockptr=>nil}], [:setlocal, 2, 0], [:getlocal, 2, 0], [:putnil], [:defineclass, module_name, ["YARVInstructionSequence/SimpleDataFormat", 2, 0, 1, {:arg_size=>0, :local_size=>1, :stack_max=>4}, "<module:#{module_name}>", "", "", 1, :class, [], 0, [], [[:putspecialobject, 1], [:putspecialobject, 2], [:putobject, method_name], [:putiseq, instructions], [:send, {:mid=>:"core#define_method", :flag=>256, :orig_argc=>3, :blockptr=>nil}], [:pop], [:putself], [:leave]]], 10], [:leave]]]))).eval
  end
end

if $0 == __FILE__

def foo
  :bar!
end

def test_it
  @it_mod = C.new.make_unbound_method(module_name: :WOAH, method_name: :haha, instructions: RubyVM::InstructionSequence.of(method(:foo)).to_a)
  @it = @it_mod.instance_method(:haha)
end

test_it
#=> #<UnboundMethod: #<Module:0x0000010123b9d0>::WOAH#haha>
@it.bind(self).call
#=> :bar!

end