Callback Results

The run_callbacks_for_* method returns a value that a given block returns.

class Smile
  Callback.enable
  define_callback_group :smile

  def smile
    run_callbacks_for_smile do
      ":)"
    end
  end
end

Record.new.smile # => ":)"

run_callbacks_for_* also stores all values returned from callbacks. You can access the returned values by the first argument of a block passed to run_callbacks_for_* or the callback_results_for_* method. You can name a callback for getting its result by the name.

class Record
  Callback.enable
  define_callback_group :validate, proc_type: Proc(Bool)

  getter name : String
  getter email : String?

  def initialize(@name, @email = nil)
  end

  on_validate :mosop? do |o|
    o.name == "mosop"
  end

  on_validate do |o|
    !o.email.nil?
  end

  def validate
    run_callbacks_for_validate do |results|
      results.values.all?
    end
  end
end

rec = Record.new(name: "mosop")
rec.validate # => false
results = rec.callback_results_for_validate
results.values # => [true, false]
results[:mosop?] # => true