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Lucas Caton

What is "frozen_string_literal" in Ruby?

Lucas Caton

Lucas Caton

Freezing Strings feature improves apps performance by freezing Strings. So, Matz - Ruby's creator - decided to make all String literals frozen (immutable) by default in Ruby 3.0.
In order to have a transition path to this coming big change, it was decided to have a magic comment at the beginning of files, so you can use in Ruby 2.x. To do so, just add this comment in the first line of your files:
# frozen_string_literal: true
class YourClass
  # ...
Try adding it to your spec_helper or rails_helper file and let me know in the comments if your performance gets any better.

More info: Ruby issue #8976.

Post updated at 02/10/2017, 10:00:00