Frozen String Literals

Frozen String Literals

Adding # frozen_string_literal: true as the very first line of a Ruby file makes every string literal in that file frozen (immutable) by default, which can improve performance by avoiding unnecessary string object allocation. This is now a common convention in Ruby projects and gems. Individual strings can still be explicitly unfrozen by calling .dup to get a mutable copy.

Note: Call .dup on a frozen string if you specifically need a mutable copy of it.

Example: Frozen String Literals

# frozen_string_literal: true

name = "Alice"
puts name.frozen?

mutable_copy = name.dup
puts mutable_copy.frozen?