class
OrderedHash
v1.1.6 -
Show latest stable
- Superclass: Array
Needs to be duplicated from Active Support since its needed before Active Support is available.
Files
- activesupport/lib/active_support/ordered_options.rb
- railties/lib/initializer.rb
1Note
is now a subclass of Hash that preserves order (or _is_ a Hash if running Ruby 1.9 or greater)
You might not realize it preserves order because it delegates inspect to its super-class, Hash, which doesn't preserve order. But you will see that order is preserved if you iterate or use the keys or values methods:
>> names = ['Amy Irving', 'Jane Doe', 'John Doe', 'John Updike', 'Susan Anthony']
>> ordered = names.group_by { |name| name.split.first }
=> #<OrderedHash {"John"=>["John Doe", "John Updike"], "Amy"=>["Amy Irving"], "Susan"=>["Susan Anthony"], "Jane"=>["Jane Doe"]}>
>> ordered.keys
=> ["Amy", "Jane", "John", "Susan"]
>> ordered.each { |first, full| puts first; full.each { |name| puts " "+name } }
Amy
Amy Irving
Jane
Jane Doe
John
John Doe
John Updike
Susan
Susan Anthony