I was wondering if I could use codes based on ruby 2.4 in ruby 3. I want to download ruby 3, but use codes based on ruby 2.4. Can I do that? I know that Ruby tries to be backwards compatible, but I would like to know if it is this backwards compatible.

CodePudding user response：

The short answer is pretty No.

You will have as many compatibility issues as many legacy code you have.

Try to reach some resources like https://www.fastruby.io/blog/ruby/rails/versions/compatibility-table.html

But still, If you have well-written tests, they will fail, and deprecation warnings will occur. Those will be some kind of map for you(by fixing issues) to reach a new version.