Overriding Array

rubyonrails-talk
1

Does anyone know how can I override ruby's Array delete method, and use my own instead?

Cheers,

Michal

2

Hi --

Does anyone know how can I override ruby's Array delete method, and use my own instead?

   class Array      def delete(obj)        ...      end    end

However, it doesn't sound like a good idea, as you'll be clobbering a core method. You'd probably be better off doing something like:

   module MyArray      def delete(obj)        ...      end    end

   a = .extend(MyArray)

David

3

put the following into lib/helpers.rb (or some other file in /lib) and then put: require 'lib/helpers.rb' into your environment.rb. Put the following into your helpers.rb file:

class Array   def delete(*arg, &block)     do my stuff   end end

Adam

4

Sure you want to do that ? :slight_smile:

I'm not sure. The rails method generated by has_many declaration returns an Array though, right? I want to be able to delete from that array, effectively destroying rows in the database through a call like @returned_array_of_my_objects.delete {|object| object.name == "name"}

Michal

5

there's an easier way of doing that..

article.rb has_many :users

users = @some_article.users

users.each {|user| user.destroy if user.name == "delete me"}

6

Sure you want to do that ? :slight_smile:

I'm not sure. The rails method generated by has_many declaration returns an Array though, right? I want to be able to delete from that array, effectively destroying rows in the database through a call like @returned_array_of_my_objects.delete {|object| object.name == "name"}

Michal

Although it masquerades as an Array, the result of a has_many association is actually an association proxy that still mixes in a large amount of ActiveRecord goodness.

From a handy script/console session:

Here's a has_many association: (see the @macro instance variable)

>> User.reflect_on_association(:favorites) => #<ActiveRecord::Reflection::AssociationReflection:0x3312290 @options={:dependent=>:destroy, :include=>:product}, @class_name="Favorite", @active_record=User, @klass=Favorite, @macro=:has_many, @primary_key_name="user_id", @through_reflection=false, @name=:favorites>

The favorites say they are what?

>> User.find(1).favorites.class => Array

Oh, really?

>> User.find(1).favorites.ancestors => [Favorite, ActiveRecord::Base, ActiveRecord::AttributeMethods, ActiveRecord::XmlSerialization, ActiveRecord::Calculations, ActiveRecord::Acts::NestedSet, ActiveRecord::Acts::List, ActiveRecord::Acts::Tree, ActiveRecord::Reflection, ActiveRecord::Transactions, ActiveRecord::Aggregations, ActiveRecord::Associations, ActiveRecord::Timestamp, ActiveRecord::Observing, ActiveRecord::Callbacks, ActiveRecord::Locking::Pessimistic, ActiveRecord::Locking::Optimistic, ActiveRecord::Validations, Reloadable::Deprecated, Object, PP::ObjectMixin, Base64::Deprecated, Base64, Kernel]

..but an Array says:

>> Array.ancestors => [Array, ActiveSupport::CoreExtensions::Array::Grouping, ActiveSupport::CoreExtensions::Array::Conversions, Enumerable, Object, PP::ObjectMixin, Base64::Deprecated, Base64, Kernel]

And in a plain irb session:

irb(main):001:0> Array.ancestors => [Array, Enumerable, Object, Kernel]

I'm not sure whether the delete with block syntax you gave will work on the "Array" (but I think that it does, try it in a safe environment), but there is a delete method of the association that takes a list of associated objects to be deleted and if they are in removed, too.

-Rob

Rob Biedenharn http://agileconsultingllc.com Rob@AgileConsultingLLC.com