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auto_vivification_nested_hashes

🐣 Auto‑Vivification of Nested Hashes​

In languages like Perl, nested hash creation is automatic. You can mimic that in Ruby by setting a default proc on the root hash that generates deeper levels on‐the‐fly.

auto_hash = Hash.new do |h, key|
  h[key] = Hash.new(&h.default_proc)
end

auto_hash[:users][:alice][:visits] = 1
puts auto_hash
#=> { users: { alice: { visits: 1 } } }

This technique avoids manual checks (h[:a] ||= {}) and elegantly supports arbitrarily deep structures, perfect for accumulating stats or building dynamic trees at runtime.