ActiveModel, run after & before callbacks separately?

Hello, is there a way to run ActiveModel callbacks separately?

Usually You do it with block (see sample below), but I have composite
model (for MongoDB, model with embedded models inside) and callbacks
should be run on all models.
In other words - the :before_create should be run on all models, after
it models will be created and after it the :after_create also should be
fired on every documents.

Actually it's possible use chain of nested blocks to do it, but in case
of ~500 nested models the stack trace will be about the same size, and
it's complicated, so I don't want to do it.

Here's the code:

  def create
    run_callbacks :create do
      # Your create action methods here
    end
  end

What I need is something like this:

  def create
    run_callbacks :before_create
    # Your create action methods here
    run_callbacks :after_create
  end

Thanks.

P.S.
Also if You need to save any plain ruby object to MongoDB (also
composite and nested) try this
https://github.com/alexeypetrushin/mongo_db

Hm the source code in ActiveSupport Callbacks is auto-generated and very
complicated (probably to optimize performance).

So, I created standalone version of callbacks, they are much simpler
(but probably not so fast as ActiveSupport Callbacks)

https://github.com/alexeypetrushin/ruby_ext/blob/master/spec/more/callbacks_spec.rb