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Feature #9108

Updated by ko1 (Koichi Sasada) almost 4 years ago

=begin
Hi,

I seem to regularly have the requirement to work on a sub-set of key/value pairs within a hash. Ruby doesn't seem to provide a concise means of selecting a sub-set of keys from a hash. To give an example of what I mean, including how I currently achieve this:

```ruby


sounds = {dog: 'woof', cat: 'meow', mouse: 'squeak', horse: 'nay', cow: 'moo'}
domestic_sounds = sounds.select { |k,v| [:dog, :cat].include? k } #=> {dog: 'woof', cat: 'meow'}
```


I think a more concise and graceful solution to this would be to allow the Hash#[] method to take multiple arguments, returning a sub-hash, e.g.

```ruby


domestic_sounds = sounds[:dog, :cat] #=> {dog: 'woof', cat: 'meow'}
```


I had a requirement in the current project I'm working on to concatenate two values in a hash. If this proposed feature existed, I could of just done this...

```ruby


sounds[:dog, :cat].values.join #=> 'woofmeow'
```


You could do something similar for the setter also...

```ruby


sounds[:monkey, :bat] = 'screech'
sounds #=> {dog: 'woof', cat: 'meow', mouse: 'squeak', horse: 'nay', cow: 'moo', monkey: 'screech', bat: 'screech'}
```


Concise, convenient and readable. Thoughts?


=end

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