callback chain ordering

callback_stack.rb

require "active_support/callbacks"

class Foo
  include ActiveSupport::Callbacks
  define_callbacks :foo

  set_callback :foo, :around, :around_1
  set_callback :foo, :before, :before_1
  set_callback :foo, :after, :after_1

  def after_1
    puts "after_1"
  end

  def before_1
    puts "before_1"
  end

  def before_2
    puts "before_2"
  end

  def around_1
    puts "around_1 top"
    yield
    puts "around_1 bottom"
  end
end

foo = Foo.new
foo.run_callbacks :foo do
  puts "in run callbacks"
end

The output is:

around_1 top
before_1
in run callbacks
after_1
around_1 bottom

ActiveSupport::Callback doesn't guarantee that all :before callbacks are called before :around callbacks. Also, the :after_1 callback is called before around_1 is finished.

关于这一段：
ActiveSupport::Callback doesn't guarantee that all :before callbacks are called before :around callbacks. Also, the :after_1 callback is called before around_1 is finished.
是你的推断还是官方文档里写的？

据我写测试code来看，执行结果是可以保证的，取决于set_callback的顺序
https://github.com/crabmc/learn_ruby_from_zero/blob/master/active_support/callback_1.rb
这段代码我跑出的结果是固定的。主要是around搀和进去容易让人理不清头绪。

顺序是固定的，没错。我原本以为顺序应该是

before_1
  around_1 top
    un run callbacks
  around_1 bottom
after_1