Feature #10523: Suggestion for new Array.delete_to method

• Status: Rejected
• Assignee: -
• Target version: -

[garysweaver (Gary Weaver)]

Array's delete and delete_at return the deleted item from an array, so it would seem as though Array should allow some sort of delete method that could take a block and would return the deleted items that matched as an array.

Currently the hack for this posted at http://stackoverflow.com/a/5480449/178651 is to use delete_if, but have to store the matched value to delete in a separate array, e.g.:

reject = []
=> []
content = [1,2,3,4,5,6,7,8,9]
=> [1, 2, 3, 4, 5, 6, 7, 8, 9]
content.delete_if {|v| reject << v if v > 5}
=> [1, 2, 3, 4, 5]
reject
=> [6, 7, 8, 9]

However, what if there were a more elegant way of doing this, like:

content = [1,2,3,4,5,6,7,8,9]
=> [1, 2, 3, 4, 5, 6, 7, 8, 9]
content.delete_to {|v| if v > 5}
=> [6, 7, 8, 9]

And you could also store the delete values in an existing array like:

content = [1,2,3,4,5,6,7,8,9]
=> [1, 2, 3, 4, 5, 6, 7, 8, 9]
content.delete_to([:a, :b]) {|v| if v > 5}
=> [:a, :b, 6, 7, 8, 9]

Or to remove and transfer the entire contents of one array to another array:

a = [1,2,3,4,5,6,7,8,9]
=> [1, 2, 3, 4, 5, 6, 7, 8, 9]
b = []
=> []
content.delete_to(b)
=> [1, 2, 3, 4, 5, 6, 7, 8, 9]
a
=> []
b
=> [1, 2, 3, 4, 5, 6, 7, 8, 9]

In which case, delete_to could be aliased as move_to.

The primary use case though is the first-it would be helpful to matching items from an array, remove them from that array, and return the removed items.

[garysweaver (Gary Weaver)]

Oops, in that last code example, I meant: a.delete_to(b).

[matz (Yukihiro Matsumoto)]

• Status changed from Open to Rejected

I prefer Array#partition for its immutability.

Matz.