From: garysweaver@...
Date: 2014-11-18T15:49:18+00:00
Subject: [ruby-core:66349] [ruby-trunk - Feature #10523] Suggestion for new Array.delete_to method

Issue #10523 has been updated by Gary Weaver.


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

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Feature #10523: Suggestion for new Array.delete_to method
https://bugs.ruby-lang.org/issues/10523#change-50002

* Author: Gary Weaver
* Status: Open
* Priority: Normal
* Assignee: 
* Category: 
* Target version: 
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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.



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