Making the methods and properties lookups inside a closure be resolved to the delegate.

marcospereira (Marcos Silva Pereira) — Fri, 15 Aug 2008 05:00:33 GMT

// The following code shows how methods and properties will be resolved to the delegate instead of the closure itself.



// creating a closure

def closure = {

    add "groovy"

    add "java"

}



// declaring a list

def list = []



// making the call methods inside closure be resolved to the list

closure.delegate = list

closure.resolveStrategy = Closure.DELEGATE_FIRST



// executing the closure

closure();



// now, the list was changed

list.each { println it }



// output 

// groovy

// java

Elegant way of shorten a text string

labuschin (Martin Labuschin) — Thu, 27 Sep 2007 11:47:15 GMT

this method shortens a plain text string down to complete words contained in given scope (count)



def shorten (string, count = 30)

	if string.length >= count 

		shortened = string[0, count]

		splitted = shortened.split(/\s/)

		words = splitted.length

		splitted[0, words-1].join(" ") + ' ...'

	else 

		string

	end

end

Extending acts_as_taggable to take scope into account

zlaj (mathieu l) — Fri, 08 Dec 2006 21:49:54 GMT

The acts_as_taggable plugin is great and so useful. But it discards scope, and it doesn't work like any other model attribute in your controller views [using normal @model.update(params[:model]) calls].

I have changed it to:
* add an alias tag_list= for tag_with (found in the "rails wiki":http://wiki.rubyonrails.com/rails/pages/ActsAsTaggablePluginHowto),
* updated find_tagged_with and count_tagged_with to use scope (after reading an article from Jamis on "ActiveRecord::Base.find":http://weblog.jamisbuck.org/2006/11/20/under-the-hood-activerecord-base-find-part-2)

Scope is used when doing this for instance:



  Message.with_scope :find => {:conditions => ["project_id = ?", @project]} do

    @messages = Message.find_tagged_with(tag.name)

  end

Then only the messages tagged with tag.name that belong to project @project.

*acts_as_taggable.rb*



module ActiveRecord

  module Acts #:nodoc:

    module Taggable #:nodoc:

      def self.included(base)

        base.extend(ClassMethods)  

      end

      

      module ClassMethods

        def acts_as_taggable(options = {})

          write_inheritable_attribute(:acts_as_taggable_options, {

            :taggable_type => ActiveRecord::Base.send(:class_name_of_active_record_descendant, self).to_s,

            :from => options[:from]

          })

          

          class_inheritable_reader :acts_as_taggable_options



          has_many :taggings, :as => :taggable, :dependent => true

          has_many :tags, :through => :taggings



          include ActiveRecord::Acts::Taggable::InstanceMethods

          extend ActiveRecord::Acts::Taggable::SingletonMethods          

        end

      end

      

      module SingletonMethods

        def find_tagged_with(list)

          tagged_with list

        end



        def count_tagged_with(list)

          tagged_with list, :count

        end



        # DRY sql query and handle scope

        protected

        def tagged_with(list, type = :find)

          if type == :count

            sql = "SELECT COUNT(DISTINCT #{table_name}.#{primary_key}) AS cnt "

          else

            sql = "SELECT DISTINCT #{table_name}.* "

          end

          sql << "FROM #{table_name}, tags, taggings "



          conditions = [

            "#{table_name}.#{primary_key} = taggings.taggable_id " +

            "AND taggings.taggable_type = ? " +

            "AND taggings.tag_id = tags.id AND tags.name IN (?) ",

            acts_as_taggable_options[:taggable_type], list

            ]

          add_conditions!(sql, conditions)



          result = find_by_sql(sql)

          (type == :count) ? result.first.cnt.to_i : result

        end



      end

      

      module InstanceMethods

        def tag_with(list)

          Tag.transaction do

            taggings.destroy_all



            Tag.parse(list).each do |name|

              if acts_as_taggable_options[:from]

                send(acts_as_taggable_options[:from]).tags.find_or_create_by_name(name).on(self)

              else

                Tag.find_or_create_by_name(name).on(self)

              end

            end

          end

        end



        # allow using active record update_attributes() and others by using tag_list to set

        # and read the tag list

        alias tag_list= tag_with



        def tag_list

          tags.collect { |tag| tag.name.include?(" ") ? "'#{tag.name}'" : tag.name }.join(" ")

        end

      end

    end

  end

end

DZone Snippets: scope code

Making the methods and properties lookups inside a closure be resolved to the delegate.

Elegant way of shorten a text string

Extending acts_as_taggable to take scope into account