[ruby-core:39590] [Ruby 1.9 - Bug #4576] Range#step miss the last value, if end-exclusive and has float number

Issue #4576 has been updated by Marc-Andre Lafortune.


I'd like to thank Vit Ondruch and Aleナ。 Mareト稿k for pointing out this issue, investigating it and providing insight as to how to fix it.

I am sorry that this problem has not been fixed yet. I completely agree that this is a bug and that Ruby_with_patch >= Ruby_without_patch.

I fail to understand how someone can think it is not a bug that should be fixed and that Ruby_with_patch < Ruby_without_patch. Or that the performance of Ruby_with_patch would be significantly affected (no performance cost has been shown, and I only own macs so I can't measure it).

I am ashamed that tests were modified to cover up the issue instead of addressing it.
I am ashamed that your repeated requests to reopen this issue were not respected.
I am ashamed that commits were made that worsen Ruby.
I am ashamed that so much arguing is going on for such an obvious defect.

I am leaving for a vacation and won't be back until November. I am unsure if I will have the time (and energy) to monitor the mailing list during that time.

With a bit of luck, when I come back, it will be accepted that `(foo...bar).step(baz).to_a.last == bar` is not acceptable. It will be accepted and remembered that floats can take between 15 and 17 digits to print. It will be obvious that committers should be allowed (if not encouraged) to write implementation independent tests in RubySpec. And respect in actions and posts will be valued.

Or maybe nothing will have changed.

I sure hope that Ruby 2.0 will not get rid of the Float class altogether, with arguments like "use BigDecimal or Rational" and "Float#== is meaningless".

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Bug #4576: Range#step miss the last value, if end-exclusive and has float number
http://redmine.ruby-lang.org/issues/4576

Author: Joey Zhou
Status: Open
Priority: Normal
Assignee: 
Category: core
Target version: 1.9.4
ruby -v: -


=begin
Hi, I find that:

* if: range.exclude_end? == true
* and: any one in [begin_obj, end_obj, step] is a true Float(f.to_i != f)
* and: unless begin_obj + step*int == end_obj
* then: the result will miss the last value.

for example:

 p (1...6.3).step.to_a # => [1.0, 2.0, 3.0, 4.0, 5.0], no 6.0
 p (1.1...6).step.to_a # => [1.1, 2.1, 3.1, 4.1], no 5.1
 p (1...6).step(1.1).to_a # => [1.0, 2.1, 3.2, 4.300000000000001], no 5.4

 p (1.0...6.6).step(1.9).to_a # => [1.0, 2.9], no 4.8
 p (1.0...6.7).step(1.9).to_a # => [1.0, 2.9, 4.8]
 p (1.0...6.8).step(1.9).to_a # => [1.0, 2.9, 4.8], no 6.7

Maybe the #step is ok on integers, but there's something wrong if the range is end-exclusive and contain float numbers.
=end



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