Callbacks are hooks into the life cycle 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 :save
end
class ConfigStorage < Storage
set_callback :save, :before, :saving_message
def saving_message
puts "saving..."
end
set_callback :save, :after do |object|
puts "saved"
end
def save
run_callbacks :save do
puts "- save"
end
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 :save
set_callback :save, :before, :prepare
def prepare
puts "preparing save"
end
end
class ConfigStorage < Storage
set_callback :save, :before, :saving_message
def saving_message
puts "saving..."
end
set_callback :save, :after do |object|
puts "saved"
end
def save
run_callbacks :save do
puts "- save"
end
end
end
config = ConfigStorage.new
config.save
Output:
preparing save saving... - save saved
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