Bug #6872: Array does not specify how it determines uniqueness of values

• Status: Closed
• Assignee: drbrain (Eric Hodel)
• Target version: -
• ruby -v: ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-darwin11.4.0]

[agrimm (Andrew Grimm)]

=begin
The documentation of (({Array#uniq})) , and similar methods, does not specify how values are determined to be unique when a block is not given.

The Stack Overflow answer http://stackoverflow.com/a/8779948/38765 explains that (({Array#uniq})) works on the basis of looking at the hash method of each value in the array. However, this is not explained in the documentation of (({Array#uniq})) , or in (({Object#hash})) .

I think, but I'm not 100% sure, that there are other methods in Array that also use the hash method, such as (({Array#-})) . Ideally, all of these methods should be documented as using the hash method.
=end

[drbrain (Eric Hodel)]

• Assignee set to drbrain (Eric Hodel)

[drbrain (Eric Hodel)]

These methods all use "Hash key equality", so #hash and #eql? control the behavior.

[robin850 (Robin Dupret)]

Hello,

I allow myself to make a patch containing documentation : https://github.com/robin850/ruby/compare/enhance_documentation

I have just a question : I was looking in the code in order to see if some methods use Object#hash when comparing elements and I found the rb_ary_eql method. Why this one doesn't end with the _p suffix ? Is there any reason please ?

Have a nice day.

[drbrain (Eric Hodel)]

Thank you, this patch looks good.

I imagine it's rb_ary_eql instead of rb_ary_eql_p due to history.

[robin850 (Robin Dupret)]

drbrain (Eric Hodel) wrote:

Thank you, this patch looks good.

I imagine it's rb_ary_eql instead of rb_ary_eql_p due to history.

I'm sorry but how are you going to merge this ? Do you want me to open a pull request on github ?

[drbrain (Eric Hodel)]

On Aug 16, 2012, at 12:40 AM, "robin850 (Robin Dupret)" [e-mail] wrote:

I'm sorry but how are you going to merge this ? Do you want me to open a pull request on github ?

If you add .patch or .diff to the github URL you get a diff.

If you'd like to create a pull request that's fine, but I'll do the exact same thing to the pull request URL to apply it.

[robin850 (Robin Dupret)]

drbrain (Eric Hodel) wrote:

On Aug 16, 2012, at 12:40 AM, "robin850 (Robin Dupret)" [e-mail] wrote:

I'm sorry but how are you going to merge this ? Do you want me to open a pull request on github ?

If you add .patch or .diff to the github URL you get a diff.

If you'd like to create a pull request that's fine, but I'll do the exact same thing to the pull request URL to apply it.

Okay, I think open a pull request it's a waste of time ; You can make the change with the URL and the .diff. Sorry for this disturbing, I'm not familiar with contributing. Have a nice day. :)

[zzak (zzak _)]

• Status changed from Open to Closed
• % Done changed from 0 to 100

This issue was solved with changeset r36965.
Andrew, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

• array.c (rb_ary_diff, rb_ary_uniq):
  Enhance documentation for array uniqueness
  Based on a patch by Robin Dupret
  [Bug #6872] [ruby-core:47209]