Feature #15976: Add Array#overlap? for whether the intersection of 2 arrays is non empty?

• Status: Closed
• Assignee: -
• Target version: -

[fcheung (Frederick Cheung)]

This is semantically equivalent to (ary1 & ary2).any?, but more efficient and makes the intent more obvious.

For example bundler checks whether the list of requested groups and the list of groups for a dependency has any overlap - it doesn't care what the overlap is, as long as it is non empty

In my personal projects we've found this to be a bottleneck when the arrays are large and where intersections are likely - !(ary1 & ary2).empty? keeps searching for all of the intersection even after we've found the first one, & creates extra garbage because of the intermediate array.

See https://github.com/ruby/ruby/pull/2260

[fcheung (Frederick Cheung)]

• File 2260.patch added
• Subject changed from Add Array#overlaps? for whether the intersection of 2 arrays is non empty? to Add Array#overlap? for whether the intersection of 2 arrays is non empty?

[fcheung (Frederick Cheung)]

• File deleted (2260.patch)

[shevegen (Robert A. Heiler)]

To me the name of the method appears to make sense and I am slightly in
favour of the suggestion. I can not say how useful this method would be
in general, though, mostly because I think I needed to do something
such as (array1 & array2).any? perhaps only once or twice in a long
time in my own code; but even then I think this might be a useful
proposal and a name that makes sense (to me at the least).

[fcheung (Frederick Cheung)]

• File deleted (2260.patch)
• File 2260.patch 2260.patch added

[fcheung (Frederick Cheung)]

• Description updated (diff)

[fcheung (Frederick Cheung)]

shevegen (Robert A. Heiler) wrote:

To me the name of the method appears to make sense and I am slightly in
favour of the suggestion. I can not say how useful this method would be
in general, though, mostly because I think I needed to do something
such as (array1 & array2).any? perhaps only once or twice in a long
time in my own code; but even then I think this might be a useful
proposal and a name that makes sense (to me at the least).

Thanks. Matz suggested today that the name was not so clear to him. An alternative that springs to mind would be intersect?, but I am obviously open to any suggestions

[janosch-x (Janosch Müller)]

I think this should be called intersect? for consistency with Set#intersect? and SortedSet#intersect?.

[matz (Yukihiro Matsumoto)]

• Status changed from Open to Feedback

I don't think overlap? is a good name. Besides that, Array#overlap? creates an internal hash table anyway, so that it wouldn't solve the bottleneck. In this case, creating a hash table explicitly would perform better.

Matz.

[matz (Yukihiro Matsumoto)]

• Is duplicate of Feature #15198: Array#intersect? added

[nobu (Nobuyoshi Nakada)]

• Status changed from Feedback to Closed

Applied in changeset git|b6bb4623ebcf1335cf0a81d279cde24a9e97bcce.

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NEWS for [Feature #15198] [ci skip]

[hsbt (Hiroshi SHIBATA)]

• Related to Feature #19839: Need a method to check if two ranges overlap added