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-rw-r--r--activesupport/lib/active_support/core_ext/enumerable.rb15
1 files changed, 15 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/core_ext/enumerable.rb b/activesupport/lib/active_support/core_ext/enumerable.rb
index 41ccc62afb..0d7d0159f9 100644
--- a/activesupport/lib/active_support/core_ext/enumerable.rb
+++ b/activesupport/lib/active_support/core_ext/enumerable.rb
@@ -30,4 +30,19 @@ module Enumerable #:nodoc:
def sum
inject(0) { |sum, element| sum + yield(element) }
end
+
+ # 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}" }
+ # => { "Chade- Fowlersburg-e" => <Person ...>, "David Heinemeier Hansson" => <Person ...>, ...}
+ #
+ def index_by
+ inject({}) do |accum, elem|
+ accum[yield(elem)] = elem
+ accum
+ end
+ end
+
end \ No newline at end of file