Issue #18083 has been updated by ioquatix (Samuel Williams). `$!` is non-trivial to implement - can have performance implications, and dynamic scope might make it more expensive. cc @Eregon @headius can we get your input? Giving `$!` dynamic scope mitigates the problem but still seems to encourage an approach that @matz has said he was against. Specifically, he was against `ensure => exception` and this is just a variant of that approach. In the first instance, the question we need to answer is: "Is there a valid use case for $! (assuming dynamic scope as proposed) that isn't better addressed using existing techniques?". If the answer is YES, we should implement it. If the answer is NO, we should deprecate and remove `$!`. ---------------------------------------- Feature #18083: Capture error in ensure block. https://bugs.ruby-lang.org/issues/18083#change-105693 * Author: ioquatix (Samuel Williams) * Status: Open * Priority: Normal ---------------------------------------- As discussed in https://bugs.ruby-lang.org/issues/15567 there are some tricky edge cases. As a general model, something like the following would be incredibly useful: ``` ruby begin ... ensure => error pp "error occurred" if error end ``` Currently you can get similar behaviour like this: ``` ruby begin ... rescue Exception => error raise ensure pp "error occurred" if error end ``` The limitation of this approach is it only works if you don't need any other `rescue` clause. Otherwise, it may not work as expected or require extra care. Also, Rubocop will complain about it. Using `$!` can be buggy if you call some method from `rescue` or `ensure` clause, since it would be set already. It was discussed extensively in https://bugs.ruby-lang.org/issues/15567 if you want more details. -- https://bugs.ruby-lang.org/