method

sum

rails latest stable - Class: Enumerable

sum(identity = nil, &block)

public

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)

# File activesupport/lib/active_support/core_ext/enumerable.rb, line 57
  def sum(identity = nil, &block)
    if identity
      _original_sum_with_required_identity(identity, &block)
    elsif block_given?
      map(&block).sum
    # we check `first(1) == []` to check if we have an
    # empty Enumerable; checking `empty?` would return
    # true for `[nil]`, which we want to deprecate to
    # keep consistent with Ruby
    elsif first.is_a?(Numeric) || first(1) == []
      identity ||= 0
      _original_sum_with_required_identity(identity, &block)
    else
      ActiveSupport::Deprecation.warn(        Rails 7.0 has deprecated Enumerable.sum in favor of Ruby's native implementation available since 2.4.        Sum of non-numeric elements requires an initial argument..squish)
      inject(:+) || 0
    end
  end

sum

Method deprecated or moved

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