Ruby 4.0.0 Released

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A new Ruby blog post/announcement has been posted!

We are pleased to announce the release of Ruby 4.0.0. Ruby 4.0 introduces “Ruby Box” and “ZJIT”, and adds many improvements.

Ruby Box

Ruby Box is a new (experimental) feature to provide separation about definitions. Ruby Box is enabled when an environment variable RUBY_BOX=1 is specified. The class is Ruby::Box.

Definitions loaded in a box are isolated in the box. Ruby Box can isolate/separate monkey patches, changes of global/class variables, class/module definitions, and loaded native/ruby libraries from other boxes.

Expected use cases are:

• Run test cases in box to protect other tests when the test case uses monkey patches to override something
• Run web app boxes in parallel to execute blue-green deployment on an app server in a Ruby process
• Run web app boxes in parallel to evaluate dependency updates for a certain period of time by checking response diff using Ruby code
• Used as the foundation (low-level) API to implement kind of “package” (high-level) API (it is not designed yet)

For the detail of “Ruby Box”, see Ruby::Box. [Feature #21311] [Misc #21385]

ZJIT

ZJIT is a new just-in-time (JIT) compiler, which is developed as the next generation of YJIT. You need Rust 1.85.0 or newer to build Ruby with ZJIT support, and ZJIT is enabled when --zjit is specified.

We’re building a new compiler for Ruby because we want to both raise the performance ceiling (bigger compilation unit size and SSA IR) and encourage more outside contribution (by becoming a more traditional method co...

Get the full details here: Ruby 4.0.0 Released | Ruby