ActiveSupport::CoreExtensions::Hash::ReverseMerge

Allows for reverse merging two hashes where the keys in the calling hash take precedence over those in the other_hash. This is particularly useful for initializing an option hash with default values:

  def setup(options = {})
    options.reverse_merge! :size => 25, :velocity => 10
  end

Using merge, the above example would look as follows:

  def setup(options = {})
    { :size => 25, :velocity => 10 }.merge(options)
  end

The default :size and :velocity are only set if the options hash passed in doesn’t already have the respective key.