From: "seanpdoyle (Sean Doyle) via ruby-core" <ruby-core@...>
Date: 2024-09-28T21:08:50+00:00
Subject: [ruby-core:119331] [Ruby master Feature#20768] Add Hash#delete_at

Issue #20768 has been reported by seanpdoyle (Sean Doyle).

----------------------------------------
Feature #20768: Add Hash#delete_at
https://bugs.ruby-lang.org/issues/20768

* Author: seanpdoyle (Sean Doyle)
* Status: Open
----------------------------------------
Add `Hash#delete_at` to delete values from a list keyed by its arguments. 

The interface and return values draw inspiration from [Hash#values_at](https://docs.ruby-lang.org/en/3.3/Hash.html#method-i-values_at) and [Array#delete_at](https://docs.ruby-lang.org/en/3.3/Array.html#method-i-delete_at). It can pair nicely with multiple assignment to deconstruct a `Hash` instance:

```ruby
hash = { a: true, b: false }
a, c = hash.delete_at(:a, :c) # => [ true, nil ]
hash # => { b: false }
```

Similar outcomes can be achieved with rightward assignment:

```ruby
hash = { a: true, b: false }
hash => { a:, **rest }
a # => true
rest # => { b: false }
```

However, rightward assignment will raise an error when a key is missing, whereas `Hash#delete_at` could return `nil` or the `Hash#default_value`:

```ruby
hash => { c: } # => raises NoMatchingPatternKeyError
```

Similarly, rightward assignment does not mutate the original `Hash` instance. In some circumstances, this is beneficial. However, others that require mutation would involve re-assigning the variable:

```ruby
hash => { a:, **hash }
a # => true
hash # => { b:false }
```

Finally, a block can be passed in the same style as [Hash#delete](https://docs.ruby-lang.org/en/3.3/Hash.html#method-i-delete) to provide a default value:

```ruby
attributes = { disabled: true, aria: { label: "label text" } }
aria, data = attributes.delete_at(:aria, :data) { Hash.new }
attributes # => { disabled: true }
aria # => { label: "label text" }
data # => {}
```



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