Ruby: Destructors?

Question

I need to occasionaly create images with rmagick in a cache dir.

To then get rid of them fast, without loosing them for the view, I want to delete the image-files wh

Answer 1

GC quirks are nice to read about, but why not properly deallocate resources according to already existing language syntax?

Let me clarify that.

class ImageDoer
  def do_thing(&block)
    image= ImageMagick.open_the_image # creates resource
    begin
      yield image # yield execution to block
    rescue
      # handle exception
    ensure
      image.destruct_sequence # definitely deallocates resource
    end
  end
end

doer= ImageDoer.new
doer.do_thing do |image|
  do_stuff_with_image # destruct sequence called if this throws
end # destruct_sequence called if execution reaches this point

Image is destroyed after the block finishes executing. Just start a block, do all the image processing inside, then let the image destroy itself. This is analogous to the following C++ example:

struct Image
{
  Image(){ /* open the image */ }
  void do_thing(){ /* do stuff with image */ }
  ~Image(){ /* destruct sequence */ }
};

int main()
{
  Image img;
  img.do_thing(); // if do_thing throws, img goes out of scope and ~Image() is called
} // special function ~Image() called automatically here