Method: ActiveSupport::Callbacks#run_callbacks

Defined in:
activesupport/lib/active_support/callbacks.rb

#run_callbacks(kind, type = nil) ⇒ Object

Runs the callbacks for the given event.

Calls the before and around callbacks in the order they were set, yields the block (if given one), and then runs the after callbacks in reverse order.

If the callback chain was halted, returns false. Otherwise returns the result of the block, nil if no callbacks have been set, or true if callbacks have been set but no block is given.

run_callbacks :save do
  save
end

–

As this method is used in many places, and often wraps large portions of user code, it has an additional design goal of minimizing its impact on the visible call stack. An exception from inside a :before or :after callback can be as noisy as it likes – but when control has passed smoothly through and into the supplied block, we want as little evidence as possible that we were here.



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# File 'activesupport/lib/active_support/callbacks.rb', line 96

def run_callbacks(kind, type = nil)
  callbacks = __callbacks[kind.to_sym]

  if callbacks.empty?
    yield if block_given?
  else
    env = Filters::Environment.new(self, false, nil)

    next_sequence = callbacks.compile(type)

    # Common case: no 'around' callbacks defined
    if next_sequence.final?
      next_sequence.invoke_before(env)
      env.value = !env.halted && (!block_given? || yield)
      next_sequence.invoke_after(env)
      env.value
    else
      invoke_sequence = Proc.new do
        skipped = nil

        while true
          current = next_sequence
          current.invoke_before(env)
          if current.final?
            env.value = !env.halted && (!block_given? || yield)
          elsif current.skip?(env)
            (skipped ||= []) << current
            next_sequence = next_sequence.nested
            next
          else
            next_sequence = next_sequence.nested
            begin
              target, block, method, *arguments = current.expand_call_template(env, invoke_sequence)
              target.send(method, *arguments, &block)
            ensure
              next_sequence = current
            end
          end
          current.invoke_after(env)
          skipped.pop.invoke_after(env) while skipped&.first
          break env.value
        end
      end

      invoke_sequence.call
    end
  end
end