Feature #14783
open
String#chars_at / String#bytes_at
Description
I just wanted to extract characters at certain indices from a string and noticed that there's no values_at counterpart for String.
I'd therefore like to propose two new String methods:
chars_at(selector, ...) → new_strbytes_at(selector, ...) → new_str
which work basically like Array#values_at, e.g.:
string = 'hello, world!' string.chars_at(0, 5, 7, 12) #=> "h,w!" string.chars_at(0..4, 7..11) #=> "helloworld" 
Updated by Hanmac (Hans Mackowiak) over 7 years ago
@sos4nt
why does it return a new string instead of array of strings?
you might like this:
string = 'hello, world!' [0, 5, 7, 12].map(&string.method(:[])).join #=> "h,w!" [0..4, 7..11].map(&string.method(:[])).join #=> "helloworld" 
Updated by zverok (Victor Shepelev) over 7 years ago
string = 'hello, world!' string.chars.values_at(0, 5, 7, 12) # => ["h", ",", "w", "!"] string.chars.values_at(0, 5, 7, 12).join # => "h,w!" ¯\_(ツ)_/¯
Updated by sos4nt (Stefan Schüßler) over 7 years ago
Hanmac (Hans Mackowiak) wrote:
why does it return a new string instead of array of strings?
Because String#[] also returns a string in such case:
a = [1, 2, 3, 4] s = "1234" a[1..2] #=> [2, 3] s[1..2] #=> "23" Accordingly:
a.values_at(1..2) #=> [2, 3] s.chars_at(1..2) #=> "23" 
Updated by nobu (Nobuyoshi Nakada) over 7 years ago
sos4nt (Stefan Schüßler) wrote:
Because
String#[]also returns a string in such case:
It's a different, single argument case.
I don't think that values_at should return same class as the receiver, as Hash#values_at.
Updated by shevegen (Robert A. Heiler) over 7 years ago
Is the frequency of #bytes_at common? I understand the use case
stated by Stefan (extract multiple indices via one method call
on a String) but #bytes_at may seem to be quite rare.
As for returning a String or Array, I personally expect #chars
on a String object to return an Array, so intuitively I would
assume #chars_at to also return an Array.