named_scope that composes other named_scopes

That's a pretty cool idea. It's similar to ticket #57 :through option for "named_scope".

I'm wondering if the :include option might be a good spot for this. Currently it's just used to manage associations, but what if you could include named scopes? This has the side benefit that you can use it in any "find" call as well as the named scope. It also would allow you to include named scopes through associations. For example:

class Category
  has_many :products
  named_scope :visible, :conditions => { :hidden => false }
end

class Product
  belongs_to :category
  named_scope :released, :conditions => "products.released_at IS NOT NULL"
  named_scope :visible, :include => [:released, {:category => :visible}]
end

Okay, probably just a crazy idea that would be ridiculously complicated to implement. But a fun thought none-the-less.