Issue #20444 has been updated by esad (Esad Hajdarevic). nobu (Nobuyoshi Nakada) wrote in #note-1:

`StopIteration.new(3)` does not set `result`, and no way to set it in Ruby level.

``` $ ruby -e 'e = StopIteration.new(3); p e.message, e.result' "3" nil ```

Thanks for the hint. It seems that subclassing StopIteration to provide result works: ``` class MyException < StopIteration def result = 5 end loop { raise MyException } # => 5 ``` ---------------------------------------- Bug #20444: Kernel#loop: returning the "result" value of StopIteration doesn't work when raised directly https://bugs.ruby-lang.org/issues/20444#change-108060 * Author: esad (Esad Hajdarevic) * Status: Closed * ruby -v: ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [arm64-darwin20] * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- There was a https://bugs.ruby-lang.org/issues/11498 a while ago which was merged in, but I was surprised to find out that raising `StopIteration` in a loop like `loop { raise StopIteration.new(3) }` returns nil and not 3. -- https://bugs.ruby-lang.org/

Issue #20444 has been updated by esad (Esad Hajdarevic). nobu (Nobuyoshi Nakada) wrote in #note-3:

I'm curious what your use case is.

Although I don't know the reason why `StopIteration#initialize` does not have the argument for `result`, it would be difficult to change it now because of the backward compatibility.

I think my use case is a bit of an edge case - I am passing a block into a Ractor where it runs in a loop. This way I can control exit from the loop, but obviously this can be also refactored into a normal result value of the block and "manual" looping control depending on the result. ---------------------------------------- Feature #20444: Kernel#loop: returning the "result" value of StopIteration doesn't work when raised directly https://bugs.ruby-lang.org/issues/20444#change-108084 * Author: esad (Esad Hajdarevic) * Status: Feedback ---------------------------------------- There was a https://bugs.ruby-lang.org/issues/11498 a while ago which was merged in, but I was surprised to find out that raising `StopIteration` in a loop like `loop { raise StopIteration.new(3) }` returns nil and not 3. -- https://bugs.ruby-lang.org/

Issue #20444 has been updated by esad (Esad Hajdarevic). ufuk (Ufuk Kayserilioglu) wrote in #note-7:

@esad If you just want to return a result from the `loop`, you can use `break <value>` to do that: ``` $ ruby -e "puts loop { break 3 }" 3

Calling break from a block passed to a ractor will raise an exception. I think some sample code about my example will be helpful: Let's make a ractor that just calls all blocks passed to it in a loop: ``` r = Ractor.new do block = Ractor.receive loop { block.call() } end ``` Now let's send it a block that raises StopIteration: ``` block = true.instance_eval { proc { raise StopIteration, 3 } } # instance_eval in true gives us a "shareable" proc r.send Ractor.make_shareable(block) r.take # => nil ``` Let's try with a subclass (this works) ``` class MyStop < ::StopIteration attr_reader :result def initialize(result) @result = result end end block = true.instance_eval { proc { raise MyStop, 3 } } r.send Ractor.make_shareable(block) r.take # => 3 ``` ---------------------------------------- Feature #20444: Kernel#loop: returning the "result" value of StopIteration doesn't work when raised directly https://bugs.ruby-lang.org/issues/20444#change-108089 * Author: esad (Esad Hajdarevic) * Status: Feedback ---------------------------------------- There was a https://bugs.ruby-lang.org/issues/11498 a while ago which was merged in, but I was surprised to find out that raising `StopIteration` in a loop like `loop { raise StopIteration.new(3) }` returns nil and not 3. -- https://bugs.ruby-lang.org/

Issue #20444 has been updated by esad (Esad Hajdarevic). nobu (Nobuyoshi Nakada) wrote in #note-9:

That example does not need `Ractor`.

Yes, you are right, it actually doesn't need Thread either, and is simply about calling a block in a loop and how to break the loop from the called block: `proc { break 3}.then { |p| loop { p.call() }}` raises exception, and `proc { raise StopIteration, 3 }.then { |p| loop { p.call() }}` returns `nil`, etc. ---------------------------------------- Feature #20444: Kernel#loop: returning the "result" value of StopIteration doesn't work when raised directly https://bugs.ruby-lang.org/issues/20444#change-108134 * Author: esad (Esad Hajdarevic) * Status: Feedback ---------------------------------------- There was a https://bugs.ruby-lang.org/issues/11498 a while ago which was merged in, but I was surprised to find out that raising `StopIteration` in a loop like `loop { raise StopIteration.new(3) }` returns nil and not 3. -- https://bugs.ruby-lang.org/