diff options
Diffstat (limited to 'activesupport/lib')
-rw-r--r-- | activesupport/lib/active_support/core_ext/enumerable.rb | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/activesupport/lib/active_support/core_ext/enumerable.rb b/activesupport/lib/active_support/core_ext/enumerable.rb index e451e9933a..fd94bc051f 100644 --- a/activesupport/lib/active_support/core_ext/enumerable.rb +++ b/activesupport/lib/active_support/core_ext/enumerable.rb @@ -64,8 +64,28 @@ module Enumerable end end + # Iterates over a collection, passing the current element *and* the + # +memo+ to the block. Handy for building up hashes or + # reducing collections down to one object. Examples: + # + # %w(foo bar).each_with_object({}) { |str, hsh| hsh[str] = str.upcase } #=> {'foo' => 'FOO', 'bar' => 'BAR'} + # + # *Note* that you can't use immutable objects like numbers, true or false as + # the memo. You would think the following returns 120, but since the memo is + # never changed, it does not. + # + # (1..5).each_with_object(1) { |value, memo| memo *= value } # => 1 + # + def each_with_object(memo, &block) + returning memo do |memo| + each do |element| + block.call(element, memo) + end + end + end unless [].respond_to?(:each_with_object) + # Convert an enumerable to a hash. Examples: - # + # # people.index_by(&:login) # => { "nextangle" => <Person ...>, "chade-" => <Person ...>, ...} # people.index_by { |person| "#{person.first_name} #{person.last_name}" } |