Bug #19622: Undocumented behavior of Array#& and similar methods

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 3.2.2 (2023-03-30 revision e51014f9c0) [arm64-darwin22]
• Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN

[tycooon (Yuri Smirnov)]

Currently, the Array#& docs only state that the objects are compared using eql? method. However, it turns out that if arrays are "big" (size more than SMALL_ARRAY_LEN), then the hash is used, so things stop working unless you also redefine hash method. I know that there is information regarding that in the eql? method docs (see https://ruby-doc.org/3.2.2/Object.html#method-i-eql-3F), however it's very likely that people will just go ahead and define the eql? method and everything will work until some point in time.

So I think it would be great to update the docs for Array methods &, intersection and intersect? to clearly state that both eql? and hash methods are used.

[tycooon (Yuri Smirnov)]

• Description updated (diff)

[tycooon (Yuri Smirnov)]

• Description updated (diff)

[tycooon (Yuri Smirnov)]

• Description updated (diff)

• Status changed from Open to Closed

Applied in changeset git|986268afae7bde07073da3ba483d12549b12801f.

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Document that Array#{&,intersection,intersect?} use hash method [ci skip]

Fixes [Bug #19622]