Module: Enumerable

Included in:
ActiveSupport::Callbacks::CallbackChain, ActiveSupport::Dependencies::WatchStack
Defined in:
lib/active_support/core_ext/enumerable.rb,
lib/active_support/core_ext/object/json.rb

Instance Method Summary collapse

Instance Method Details

#as_json(options = nil) ⇒ Object

:nodoc:



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# File 'lib/active_support/core_ext/object/json.rb', line 127

def as_json(options = nil) #:nodoc:
  to_a.as_json(options)
end

#exclude?(object) ⇒ Boolean

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

Returns:

  • (Boolean) 


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

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

#index_by ⇒ Object

Convert an enumerable to a hash.

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



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# File '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

#many? ⇒ Boolean

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.

Returns:

  • (Boolean) 


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# File '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

#sum(identity = 0, &block) ⇒ Object

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)



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# File '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