Seven steps

An auto-vivifying hash is a hash that lets you create sub-hashes automatically. This means that the following code becomes possible:

def cnh # silly name "create nested hash"
  Hash.new {|h,k| h[k] = Hash.new(&h.default_proc)}
end
my_hash = cnh
my_hash[1][2][3] = 4
my_hash # => { 1 => { 2 => { 3 =>4 } } }

This is useful because it reduces the amount of logic in the code. No more “If sub-hash doesn’t exist, create it!”

Courtesy of Robert Klemme on www.ruby-forum.com

Send to:

Tags: ruby

This entry was posted on Friday, November 6th, 2009 at 8:27 am and is filed under ruby. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.