Ruby 3.4 frozen string literal deprecation warnings

[PhilMeyr]

Description

When using inky-rb with Ruby 3.4, deprecation warnings are emitted about frozen string literals.

Warning message

lib/inky/component_factory.rb:137: warning: literal string will be frozen in the future

Environment

• Ruby version: 3.4.x
• inky-rb version: 1.4.2.1

Root cause

In Ruby 3.4, string literals will be frozen by default in the future. The code at line 137 of lib/inky/component_factory.rb modifies a string literal in place, which triggers this deprecation warning.

Suggested fix

Replace in-place string modification with a new string allocation, for example:

• Use string interpolation instead of prepend/<<
• Use dup before modifying the string
• Use +'' to create a mutable copy

This is similar to the fix applied in other gems like marcel (rails/marcel#140).

[PhilMeyr]

Context: This appears to be related to a known Ruby issue.

See Ruby issue #21280 - these warnings were identified as false positives by Matz. The code should work correctly when strings are frozen by default.

As of Ruby 3.4.7, the warnings are still present in Ruby itself. Just sharing this context for reference.

[joeworkman]

This repository is being sunset. The Inky project is being rewritten in Rust with a single canonical core and official bindings for all major languages — including a new Ruby gem that uses the shared Rust core via FFI (fiddle).

This means:

• One implementation, identical output across all languages
• No more Ruby-specific bugs or maintenance burden
• The new Ruby gem will have zero gem dependencies (fiddle is in Ruby's stdlib)

You can follow progress at https://github.com/foundation/inky.

Thanks for using inky-rb!