Feature #16350

ArithmeticSequence#member? can result in infinite loop

Added by parker (Parker Finch) over 1 year ago. Updated 9 months ago.

Target version:


I'm not sure if this is a bug or a feature, it feels somewhere in between.

This is my first time contributing to the Ruby code, let me know what I can improve in this report!

ArithmeticSequence#member? enumerates through the sequence in order to determine if an element is included. (It just uses Enumerable#member?.) This leads to an infinite loop if the sequence is infinite and the element is not included, such as 1.step.member?(0).

I expected 1.step.member?(0) to return false.

Since ArithmeticSequences are much more constrained than regular Enumerables, the #member? method can be overridden to efficiently determine if an element is included in the sequence.

I started implementing this change (patch attached) but got a little confused when trying to handle floats. Before digging in too deeply, I wanted to check if this is a change that will be accepted.

Let me know if I should keep looking into this!


0001-Start-implementing-ArithmeticSequence-member.patch (3.96 KB) 0001-Start-implementing-ArithmeticSequence-member.patch patch (unfinished implementation, tests currently fail) parker (Parker Finch), 11/16/2019 05:10 PM

Updated by nobu (Nobuyoshi Nakada) over 1 year ago

  • Assignee set to mrkn (Kenta Murata)
  • Status changed from Open to Assigned

Updated by jeremyevans0 (Jeremy Evans) 9 months ago

  • Backport deleted (2.5: UNKNOWN, 2.6: UNKNOWN)
  • ruby -v deleted (ruby 2.7.0dev)
  • Tracker changed from Bug to Feature

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