Does has_many collection '<<' (append operator) always save/create child in DB when parent isn't new?

Howdy, the title mostly asks the question.

Given the following:

class Article < ActiveRecord::Base ; has_many :comments ; end class Comment < ActiveRecord::Base ; belongs_to :article ; end

I have an article already instantiated in the database, referenced as @article.

Will the following code always "create" (save to DB) a new comment?

@article.comments << :text => "Blah blah..."

I would like to be able to add comments to an article that already already exists (and may already have comments that exist) in the database w/out the new comment being saved to the database.

I would try this: :text => "Blan blah..."

The reason I don't is because my Comment class is sub-classed using STI. Thus, my code really looks more like this:

klass = Comment.get_class(params[:comment_type]) # get_class returns Comment or a sub-type @article.comments << :text => "Blah blah..."

Anyone have any ideas on how I can add STI comments to an article w/ out saving them, doing so "the right way" (I'm sure I could ugly-hack it)?