Fix returning a new instance of the uploader on every uploader call

[DarthSim]

How to reproduce:

class Picture < ActiveRecord::Base
  mount_uploader :image, ImageUploader
end

pic = Picture.new
pic.image.object_id # => 70317811568320
pic.image.object_id # => 70317821530860

First of all, this bug generates new objects every time, and this is definitely not good. Also this affects on actions with uploader. For example:

pic = Picture.new
pic.image.retrieve_from_cache!("1454349370-83816-0001-5310/image.jpg")
pic.image.blank? # => true

[mehlah]

LGTM 👍

[thomasfedb]

Looks like a sensible change @DarthSim. My only query before I can merge this is if it keeps the single and plural mounters consistent. Could you check this please?

[DarthSim]

@thomasfedb It does, why shouldn't it?

[thomasfedb]

@DarthSim I just wanted to compare the behaviour of these two:

def mount_uploader(column, uploader=nil, options={}, &block)
  # ...

  def #{column}
    _mounter(:#{column}).uploaders[0] ||= _mounter(:#{column}).blank_uploader
  end

def mount_uploaders(column, uploader=nil, options={}, &block)
  # ...

  def #{column}
    _mounter(:#{column}).uploaders
  end

[thomasfedb]

Clearly you changes makes this more consistent, as the later example was already returning a stable object.