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Module: Enumerable

Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Included In:
ActionController::MiddlewareStack, ActionController::RequestForgeryProtection::ProtectionMethods::NullSession::NullCookieJar, ActionDispatch::Cookies::CookieJar, ::ActionDispatch::Flash::FlashHash, ::ActionDispatch::Http::Headers, ActionDispatch::Journey::Nodes::Binary, ActionDispatch::Journey::Nodes::Cat, ActionDispatch::Journey::Nodes::Dummy, ActionDispatch::Journey::Nodes::Group, ActionDispatch::Journey::Nodes::Literal, ActionDispatch::Journey::Nodes::Node, ActionDispatch::Journey::Nodes::Or, ActionDispatch::Journey::Nodes::Star, ActionDispatch::Journey::Nodes::Symbol, ActionDispatch::Journey::Nodes::Terminal, ActionDispatch::Journey::Nodes::Unary, ActionDispatch::Journey::Routes, ::ActionDispatch::MiddlewareStack, ActionDispatch::Routing::RouteSet::NamedRouteCollection, ActionView::PathSet, ::ActiveModel::Errors, ::ActiveRecord::Associations::JoinDependency::JoinAssociation, ActiveRecord::Associations::JoinDependency::JoinBase, ActiveRecord::Associations::JoinDependency::JoinPart, ::ActiveRecord::ConnectionAdapters::MysqlAdapter::StatementPool, ::ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::StatementPool, ::ActiveRecord::ConnectionAdapters::SQLite3Adapter::StatementPool, ::ActiveRecord::ConnectionAdapters::StatementPool, ActiveRecord::Fixture, ActiveRecord::FixtureSet::File, ::ActiveRecord::Result, ::ActiveSupport::Callbacks::CallbackChain, ::ActiveSupport::Dependencies::WatchStack, ::Mysql::Result, ::Mysql::Stmt, ::Rails::Engine::Railties, ::Rails::Paths::Path
Defined in: activesupport/lib/active_support/core_ext/enumerable.rb,
activesupport/lib/active_support/core_ext/object/json.rb

Instance Attribute Summary

Instance Method Summary

Instance Attribute Details

#many? ⇒ Boolean (readonly)

Returns true if the enumerable has more than 1 element. Functionally equivalent to enum.to_a.size > 1. Can be called with a block too, much like any?, so people.many? { |p| p.age > 26 } returns true if more than one person is over 26.

[ GitHub ] 

  


# File 'activesupport/lib/active_support/core_ext/enumerable.rb', line 46



def many?
  cnt = 0
  if block_given?
    any? do |element|
      cnt += 1 if yield element
      cnt > 1
    end
  else
    any? { (cnt += 1) > 1 }
  end
end


  







Instance Method Details



  

    #exclude?(object)  ⇒ Boolean 
  



  

    

The negative of the Enumerable#include?. Returns true if the collection does not include the object.


  





  


  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/enumerable.rb', line 60



def exclude?(object)
  !include?(object)
end


  








  

    #index_by  
  



  

    

Convert an enumerable to a hash.



people.index_by(&:)
  #=> { "nextangle" => <Person ...>, "chade-" => <Person ...>, ...}
people.index_by { |person| "#{person.first_name} #{person.last_name}" }
  #=> { "Chade- Fowlersburg-e" => <Person ...>, "David Heinemeier Hansson" => <Person ...>, ...}


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/enumerable.rb', line 34



def index_by
  if block_given?
    Hash[map { |elem| [yield(elem), elem] }]
  else
    to_enum(:index_by) { size if respond_to?(:size) }
  end
end


  








  

    #sum(identity = 0, &block)  
  



  

    

Calculates a sum from the elements.



payments.sum { |p| p.price * p.tax_rate }
payments.sum(&:price)



The latter is a shortcut for:



payments.inject(0) { |sum, p| sum + p.price }



It can also calculate the sum without the use of a block.



[5, 15, 10].sum # => 30
['foo', 'bar'].sum # => "foobar"
[[1, 2], [3, 1, 5]].sum => [1, 2, 3, 1, 5]



The default sum of an empty list is zero. You can override this default:



[].sum(Payment.new(0)) { |i| i.amount } # => Payment.new(0)


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/core_ext/enumerable.rb', line 20



def sum(identity = 0, &block)
  if block_given?
    map(&block).sum(identity)
  else
    inject { |sum, element| sum + element } || identity
  end
end