diff options
Diffstat (limited to 'activesupport/lib/active_support/ordered_hash.rb')
| -rw-r--r-- | activesupport/lib/active_support/ordered_hash.rb | 18 |
1 files changed, 10 insertions, 8 deletions
diff --git a/activesupport/lib/active_support/ordered_hash.rb b/activesupport/lib/active_support/ordered_hash.rb index e19d9d7dc1..2e8d538d0b 100644 --- a/activesupport/lib/active_support/ordered_hash.rb +++ b/activesupport/lib/active_support/ordered_hash.rb @@ -4,15 +4,17 @@ YAML.add_builtin_type("omap") do |type, val| ActiveSupport::OrderedHash[val.map(&:to_a).map(&:first)] end -# Hash is not ordered in ruby 1.8.x. What it means is there is no guarantee of order of keys when -# method Hash#keys in invoked. Similarly Hash#values and Hash#each can't guarantee that each time -# the output will contain exactly same value in the same order. <tt>OrderedHash</tt> solves that -# problem. -# -# ActiveSupport::OrderedHash[:boy, 'John', :girl, 'Mary'] -# -# OrderedHash is namespaced to prevent conflicts with other implementations. module ActiveSupport + # The order of iteration over hashes in Ruby 1.8 is undefined. For example, you do not know the + # order in which +keys+ will return keys, or +each+ yield pairs. <tt>ActiveSupport::OrderedHash</tt> + # implements a hash that preserves insertion order, as in Ruby 1.9: + # + # oh = ActiveSupport::OrderedHash.new + # oh[:a] = 1 + # oh[:b] = 2 + # oh.keys # => [:a, :b], this order is guaranteed + # + # <tt>ActiveSupport::OrderedHash</tt> is namespaced to prevent conflicts with other implementations. class OrderedHash < ::Hash #:nodoc: def to_yaml_type "!tag:yaml.org,2002:omap" |