Hi,
Just wondering when one would use “include” over “extend”? Both seem to
bring in methods to the class no?
The context is I’m just trying to understand why both are used with the
acts_as_audited plugin:
Full extract from plugin (used within here):
Copyright © 2006 Brandon K.
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
“Software”), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
module CollectiveIdea #:nodoc:
module Acts #:nodoc:
Specify this act if you want changes to your model to be saved in
an
audit table. This assumes there is an audits table ready.
class User < ActiveRecord::Base
acts_as_audited
end
See
CollectiveIdea::Acts::Audited::ClassMethods#acts_as_audited
for configuration options
module Audited
CALLBACKS = [:clear_changed_attributes, :audit_create,
:audit_update, :audit_destroy]
def self.included(base) # :nodoc:
base.extend ClassMethods
end
module ClassMethods
# == Configuration options
#
# * <tt>except</tt> - Excludes fields from being saved in the
audit log.
# By default, acts_as_audited will audit all but these fields:
#
# [self.primary_key, inheritance_column, ‘lock_version’,
‘created_at’, ‘updated_at’]
#
# You can add to those by passing one or an array of fields to
skip.
#
# class User < ActiveRecord::Base
# acts_as_audited :except => :password
# end
#
# * user_class_name - specifiy the class name of the
user class.
# This defaults to “User”. Set to false to disable user
auditing.
#
# * user_method - specify the method to call on
:user_class_name
# that returns the user that is performing the action. This
defaults to
# :current_user.
#
# == Database Schema
#
def acts_as_audited(options = {})
# don’t allow multiple calls
return if
self.included_modules.include?(CollectiveIdea::Acts::Audited::InstanceMethods)
include CollectiveIdea::Acts::Audited::InstanceMethods
class_eval do
extend CollectiveIdea::Acts::Audited::SingletonMethods
cattr_accessor :non_audited_columns,
:audited_user_class_name, :audited_user_method
self.non_audited_columns = [self.primary_key,
inheritance_column, ‘lock_version’, ‘created_at’, ‘updated_at’]
self.non_audited_columns |= options[:except].is_a?(Array) ?
options[:except].collect{|column| column.to_s} :
[options[:except].to_s] if options[:except]
self.audited_user_class_name =
options[:user_class_name].nil? ? “User” : options[:user_class_name]
self.audited_user_method = options[:user_method] ||
:current_user
has_many :audits, :as => :auditable
after_create :audit_create
after_update :audit_update
before_destroy :audit_destroy
after_save :clear_changed_attributes
end
end
end
module InstanceMethods
# Temporarily turns off auditing while saving.
def save_without_auditing
without_auditing do
save
end
end
# Returns an array of attribute keys that are audited. See
non_audited_columns
def audited_attributes
self.attributes.keys.select { |k|
!self.class.non_audited_columns.include?(k) }
end
# If called with no parameters, gets whether the current model
has changed.
# If called with a single parameter, gets whether the parameter
has changed.
def changed?(attr_name = nil)
attr_name.nil? ?
(@changed_attributes && @changed_attributes.length > 0) :
(@changed_attributes &&
@changed_attributes.include?(attr_name.to_s))
end
# Executes the block with the auditing callbacks disabled.
#
# @foo.without_auditing do
# @foo.save
# end
#
def without_auditing(&block)
self.class.without_auditing(&block)
end
private
# Creates a new record in the audits table if applicable
def audit_create
logger.debug "ACTS AS: audit_create"
write_audit(:create)
end
def audit_update
write_audit(:update) if changed?
end
def audit_destroy
write_audit(:destroy)
end
def write_audit(action = :update)
logger.debug "ACTS AS: write_audit"
logger.debug "ACTS AS: self.audited_user_class_name =
#{self.audited_user_class_name}"
#logger.debug “ACTS AS:
Object.const_get(audited_user_class_name) =
#{Object.const_get(audited_user_class_name)}”
logger.debug “ACTS AS: self.audited_user_method =
#{self.audited_user_method}”
user = self.audited_user_class_name ?
Object.const_get(audited_user_class_name).send(self.audited_user_method)
: nil
logger.debug "ACTS AS: user = #{user}"
audits.create(:changes => @changed_attributes,
:action =>
action.to_s,
:user_id => user ? user.id : nil)
end
# clears current changed attributes. Called after save.
def clear_changed_attributes
@changed_attributes = {}
end
# overload write_attribute to save changes to audited
attributes
def write_attribute(attr_name, attr_value)
attr_name = attr_name.to_s
if audited_attributes.include?(attr_name)
@changed_attributes ||= {}
# get original value
old_value = @changed_attributes[attr_name] ?
@changed_attributes[attr_name].first : self[attr_name]
super(attr_name, attr_value)
new_value = self[attr_name]
@changed_attributes[attr_name] = [old_value, new_value] if
new_value != old_value
else
super(attr_name, attr_value)
end
end
CALLBACKS.each do |attr_name|
alias_method "orig_#{attr_name}".to_sym, attr_name
end
def empty_callback() end #:nodoc:
end # InstanceMethods
module SingletonMethods
# Returns an array of columns that are audited. See
non_audited_columns
def audited_columns
self.columns.select { |c|
!non_audited_columns.include?(c.name) }
end
# Executes the block with the auditing callbacks disabled.
#
# Foo.without_auditing do
# @foo.save
# end
#
def without_auditing(&block)
class_eval do
CALLBACKS.each do |attr_name|
alias_method attr_name, :empty_callback
end
end
result = block.call
class_eval do
CALLBACKS.each do |attr_name|
alias_method attr_name, "orig_#{attr_name}".to_sym
end
end
result
end
end
end
end
end
ActiveRecord::Base.send :include, CollectiveIdea::Acts::Audited
==================================================
What you’re seeing, among other things, is a class being
… but if you do understand and