[ruby-core:46929] [ruby-trunk - Feature #6824][Open] StopIteration gets a source method

Issue #6824 has been reported by jasiek (Jan Szumiec).

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Feature #6824: StopIteration gets a source method
https://bugs.ruby-lang.org/issues/6824

Author: jasiek (Jan Szumiec)
Status: Open
Priority: Normal
Assignee: 
Category: core
Target version: 2.0.0


I'd like to add a method to StopIteration that returns an instance of the enumerator which triggered this exception. Eg:

enum = [].each
begin
  enum.next
rescue StopIteration => ex
  puts "same" if ex.source == enum
end

This is useful when you're merging multiple collections using min/max - when one of the collections is exhausted it can be easily ignored.

enumerators = 100.times.map do
  rand(100).times.map do
    rand
  end.sort.each
end

merged = []
while !enumerators.empty?
  begin
    enumerators.map(&:peek)
    values = enumerators.map(&:next)

    merged += values.sort
  rescue StopIteration => e
    enumerators.delete(e.source)
    retry
  end
end

fail unless merged != merged.sort

Attached is a patch against trunk.




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