Module: Enumerable

Defined in:
lib/gorillib/enumerable/sum.rb

Instance Method Summary collapse

Instance Method Details

#sum(identity = 0, &block) ⇒ Object

Calculates a sum from the elements. Examples:

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/gorillib/enumerable/sum.rb', line 22

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