Issue #16678 has been updated by Eregon (Benoit Daloze).


You can easily achieve wrap-around behavior with:
```ruby
> (1..5).to_a.values_at(*(-1..3))
=> [5, 1, 2, 3, 4]
```

Using a Range for `values_at` is like taking a slice with `Array#[]/slice`, and Array slices never wrap around (a good thing IMHO, that would be expensive to compute and confusing).

----------------------------------------
Misc #16678: Array#values_at has unintuitive behavior when supplied a range starting with negative index
https://bugs.ruby-lang.org/issues/16678#change-84532

* Author: prajjwal (Prajjwal Singh)
* Status: Open
* Priority: Normal
----------------------------------------
Consider the following:

``` ruby
# frozen_string_literal: true

a = (1..5).to_a

p a.values_at(3..5) # => [4, 5, nil]
p a.values_at(-1..3)  # => []
```

When the range begins with a negative `(-1, 0, 1, 2, 3)`, it returns an empty array, which surprised me because I was expecting `[1, 2, 3, 4]`.

The argument for this is that it cold be confusing to allow this because the index `-1` could refer to the last argument and it would be unintuitive to return an array `[5, 1, 2, 3, 4]` with jumbled values.

The argument against it is that it makes perfect sense to account for this case and return `[nil, 1, 2, 3, 4]`.

Opening a dialog to see what others think of this.




-- 
https://bugs.ruby-lang.org/

Unsubscribe: <mailto:ruby-core-request / ruby-lang.org?subject=unsubscribe>
<http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>