j_ruby.rb

Kernel.class_eval do
  #FIXME this is terrible
  def static(meth)
    define_singleton_method(meth) do |*args, &b|
      new.send meth, *args, &b
    end
    meth
  end

  def abstract(meth)
    define_method(meth) { raise "Please implement #{self.class.name}##{meth}." }
    meth
  end

  def final(meth)
    self.extend Module.new { define_method(:method_added) {|added_meth| raise("Overriding or redefining #{meth} is prohibited.") if added_meth == meth; super(added_meth); } }
    meth
  end

  def native(meth)
    meth
  end

  def friend(meth)
    #TODO
    meth
  end

  def synchronized(meth)
    #TODO
    meth
  end

  def void(meth)
    meth
  end

  def virtual(meth)
    meth
  end

  def override(meth)
    raise "#{self.name}##{meth} is not defined." unless ancestors[1..-1].any? {|a| a.method_defined? meth }
    meth
  end
end

class Hello
  abstract void def aaa
  p :aaaaa
  end
  public static final void def main(*)
    puts 'hello, world'
  end
end

class Hello2 < Hello
  override def aaa
    p 'hello2'
  end
end

Hello2.new.aaa
Hello.main
#=> hello, world

override は arity の一致をチェックしたほうがいいかもしれません。あと、finalと競合するとか。

overrideはやっぱり、＠Overrideにした方が!