[ruby-core:84576] [Ruby trunk Feature#9145] Queue#pop(true) return nil if empty instead of raising ThreadError

Issue #9145 has been updated by [e-mail] (Uwe Kubosch).


How about a block form where the block is called with the popped element?  The method would return false if called with non_block set to true if the queue is empty.

q = Queue.new
q << 1
q << 2
q << 3

while q.pop(true){|x| p x}


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Feature #9145: Queue#pop(true) return nil if empty instead of raising ThreadError
https://bugs.ruby-lang.org/issues/9145#change-69116

* Author: jsc (Justin Collins)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
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I propose the non-blocking form of Queue#pop behave like Array#pop and return nil when empty.

Current behavior is to raise a ThreadError, with a message indicating the queue is empty.

For example:

q = Queue.new
begin
  loop do
    next_item = q.pop(true)
  end
rescue ThreadError
  # queue is empty...or maybe something bad happened
end

Instead, this could be

q = Queue.new
while next_item = q.pop(true)
end

Alternatively, raise an exception that is a subclass of ThreadError with a more specific name, such as "QueueEmpty". This would be a small improvement while remaining compatible with existing code.



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