Issue #17357 has been updated by naruse (Yui NARUSE).

Status changed from Open to Feedback

Do you have a use case?

The issue is well discussed in [Feature #10600] and concluded as current spec.
To discuss again we need new materials.

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Feature #17357: `Queue#pop` should have a block form for clsoed queues
https://bugs.ruby-lang.org/issues/17357#change-89079

* Author: marcandre (Marc-Andre Lafortune)
* Status: Feedback
* Priority: Normal
----------------------------------------
It is currently difficult to reliably distinguish a `nil` value in a queue from the `nil` that is returned when a Queue is closed:

```ruby
n = 100_000
result = []
t2 = Thread.new { n.times { Thread.pass }} # to make things less predictable
n.times.count do
  q = Queue.new
  t = Thread.new { q.pop; result << q.closed? }
  q << nil
  q.close
  t.join
end
puts result.count(true) # => some number usually > 9990 and < 10000
````

To be completely sure, one needs a Mutex or wrap/unwrap `nil` values.

`Queue#pop` should offer a surefire way to handle closed queues. I propose that an optional block be called in this case:

```ruby
q = Queue.new.close
q.pop # => nil
q.pop { :closed }  # => :closed
````

Proposed PR: https://github.com/ruby/ruby/pull/3830



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