Is auto-initialization of multi-dimensional hash array possible in Ruby, as it is in PHP?

I am so used to work in PHP with multi-dimensional arrays, where I can assign and initialize a hash by

unset($a); // just to show that there is no variable $a
$a['settings']['system']['memory'] = '1 Gb';
$a['settings']['system']['disk space'] = '100 Gb';

Is there a way to do similar thing in Ruby? Or I need to initialize all dimensions first, and then to assign values. Is it possible to define an advanced Hash which will allow to do what I need? How would you do that?


In addition to the solution proposed by Douglas (see below), I have found a thread on the subject, in which Brian Schröäer has proposed an extension for the Hash class:

class AutoHash < Hash
  def initialize(*args)
    @update, @update_index = args[0][:update], args[0][:update_key] unless args.empty?

  def [](k)
    if self.has_key?k
    else => self, :update_key => k)

  def []=(k, v)
    @update[@update_index] = self if @update and @update_index

It allows to solve the problem when a missing hash item is undesirably created when the item value was only requested, e.g. a['key'].

Some additional references

  1. ruby hash autovivification (facets)

Here is Solutions:

We have many solutions to this problem, But we recommend you to use the first solution because it is tested & true solution that will 100% work for you.

Solution 1

Try this:

def hash_with_default_hash { |hash, key| hash[key] = hash_with_default_hash }

a = hash_with_default_hash

If the key doesn’t exist, then the result of the block will be used as the default value. In this case, the default value is also a hash which uses hashes as its default values.

Note: Use and implement solution 1 because this method fully tested our system.
Thank you 🙂

All methods was sourced from or, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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