ActiveSupport::Callbacks

Callbacks are hooks into the lifecycle of an object that allow you to trigger logic before or after an alteration of the object state.

Mixing in this module allows you to define callbacks in your class.

Example:

  class Storage
    include ActiveSupport::Callbacks

    define_callbacks :before_save, :after_save
  end

  class ConfigStorage < Storage
    before_save :saving_message
    def saving_message
      puts "saving..."
    end

    after_save do |object|
      puts "saved"
    end

    def save
      run_callbacks(:before_save)
      puts "- save"
      run_callbacks(:after_save)
    end
  end

  config = ConfigStorage.new
  config.save

Output:

  saving...
  - save
  saved

Callbacks from parent classes are inherited.

Example:

  class Storage
    include ActiveSupport::Callbacks

    define_callbacks :before_save, :after_save

    before_save :prepare
    def prepare
      puts "preparing save"
    end
  end

  class ConfigStorage < Storage
    before_save :saving_message
    def saving_message
      puts "saving..."
    end

    after_save do |object|
      puts "saved"
    end

    def save
      run_callbacks(:before_save)
      puts "- save"
      run_callbacks(:after_save)
    end
  end

  config = ConfigStorage.new
  config.save

Output:

  preparing save
  saving...
  - save
  saved