One liner nested hash creation in Ruby? (I come from Perl)

Question

I am a Perl person and I have made Hashes like this for a while:

 my %date;  #Assume the scalars are called with 'my' earlier  $date{$month}{$day}{$hours}{$min}{$sec}++ 

Now I am learning Ruby and I have so far found that using this tree is the way to do many keys and a value. Is there any way to use the simple format that I use with Perl using one line?

  @date = {                                                                                                                                                                               month => {                                                                                                                                                                            day => {                                                                                                                                                                             hours => {                                                                                                                                                                             min => {                                                                                                                                                                              sec => 1                                                                                                                                                                          }                                                                                                                                                                                 }                                                                                                                                                                                 }                                                                                                                                                                                 }                                                                                                                                                                                                                                                                                                                                                            }                    

Answer 1

Unfortunately, there is no simple, practical way. A Ruby equivalent would be an ugly, ugly beast like:

((((@date[month] ||= {})[day] ||= {})[hours] ||= {})[min] ||= {})[sec] = 1 

There is a way to assign default values for missing keys in hashes, though:

@date = Hash.new { |hash, key| hash[key] = {} }  # @date[:month] is set to a new, empty hash because the key is missing. @date[:month][:day] = 1 

Unfortunately this does not work recursively.

...unless you create it yourself; hooray for Ruby!

class Hash   def self.recursive     new { |hash, key| hash[key] = recursive }   end end  @date = Hash.recursive @date[month][day][hours][min][sec] = 1 # @date now equals {month=>{day=>{hours=>{min=>{sec=>1}}}}} 

Keep in mind, though, that all unset values are now {} rather than nil.