vendor/rails/activesupport/lib/active_support/core_ext/hash/reverse_merge.rb

   1 module ActiveSupport #:nodoc:
   2   module CoreExtensions #:nodoc:
   3     module Hash #:nodoc:
   4       # Allows for reverse merging two hashes where the keys in the calling hash take precedence over those
   5       # in the <tt>other_hash</tt>. This is particularly useful for initializing an option hash with default values:
   6       #
   7       #   def setup(options = {})
   8       #     options.reverse_merge! :size => 25, :velocity => 10
   9       #   end
  10       #
  11       # Using <tt>merge</tt>, the above example would look as follows:
  12       #
  13       #   def setup(options = {})
  14       #     { :size => 25, :velocity => 10 }.merge(options)
  15       #   end
  16       #
  17       # The default <tt>:size</tt> and <tt>:velocity</tt> are only set if the +options+ hash passed in doesn't already
  18       # have the respective key.
  19       module ReverseMerge
  20         # Performs the opposite of <tt>merge</tt>, with the keys and values from the first hash taking precedence over the second.
  21         def reverse_merge(other_hash)
  22           other_hash.merge(self)
  23         end
  24
  25         # Performs the opposite of <tt>merge</tt>, with the keys and values from the first hash taking precedence over the second.
  26         # Modifies the receiver in place.
  27         def reverse_merge!(other_hash)
  28           replace(reverse_merge(other_hash))
  29         end
  30
  31         alias_method :reverse_update, :reverse_merge!
  32       end
  33     end
  34   end
  35 end