symbol_pattern_matching

🎯 Advanced Pattern Matching with Symbol Keys

Ruby 2.7+ introduces structural pattern matching, with symbols frequently serving as hash keys in deconstructable data. Use concise case in expressions to match nested hashes and arrays, extracting values into local variables with minimal ceremony.

response = { status: :ok, data: { id: 42, name: "Alice" } }

case response
in { status: :ok, data: { id:, name: } }
  puts "User ##{id}: #{name}"
in { status: :error, error: message }
  warn "Error: #{message}"
end

You can also match array payloads with symbol constants:

message = [:update, :cache, { key: "user:1", value: user_data }]

case message
in [:update, :cache, { key:, value: }]
  update_cache(key, value)
end