Feature #19302
closedNon-destructive String#insert
Description
It would be nice to have a non-destructive version of String#insert to be able to work with frozen literals.
Current behavior¶
There is only a destructive version of String#insert
that will throw an error if the string is frozen.
irb(main):007:0> a = 'foobar'.freeze
irb(main):008:0> b = a.insert(3,'baz')
(irb):8:in `insert': can't modify frozen String: "foobar" (FrozenError)
from (irb):8:in `<main>'
from /home/noraj/.asdf/installs/ruby/3.2.0/lib/ruby/gems/3.2.0/gems/irb-1.6.2/exe/irb:11:in `<top (required)>'
from /home/noraj/.asdf/installs/ruby/3.2.0/bin/irb:25:in `load'
from /home/noraj/.asdf/installs/ruby/3.2.0/bin/irb:25:in `<main>'
This can happen pretty quickly when you have # frozen_string_literal: true
in all your files.
Idea of implementation¶
def insert_nd(idx, str2)
self[0...idx] + str2 + self[idx..]
end
Note: this is a draft, as it doesn't handle negative index in the same way as insert
Idea of naming¶
Ideally the actual String#insert
would have been String#insert!
so that the non-destructive version could be String#insert
, but naturally that won't do as a renaming will cause a breaking change.
A more viable option would be to name it insert_nd
(nd for non-destructive) but it's may not be following a naming convention.
Another idea to avoid confusion would be to avoid using insert
and rather use a synonym like place, slip, slot, lodge, etc.
Updated by noraj (Alexandre ZANNI) almost 2 years ago
- Tracker changed from Bug to Feature
- ruby -v deleted (
ruby 3.2.0 (2022-12-25 revision a528908271) [x86_64-linux]) - Backport deleted (
2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN)
Updated by austin (Austin Ziegler) almost 2 years ago
Ruby strings are mostly copy-on-write, so string.dup.insert(3, 'baz')
would solve the issue, and it could be written (I believe) as -string.insert(3, 'baz')
in modern Ruby.
Updated by jeremyevans0 (Jeremy Evans) almost 2 years ago
austin (Austin Ziegler) wrote in #note-2:
Ruby strings are mostly copy-on-write, so
string.dup.insert(3, 'baz')
would solve the issue, and it could be written (I believe) as-string.insert(3, 'baz')
in modern Ruby.
-string.insert(3, 'baz')
is parsed as -(string.insert(3, 'baz'))
, which is not the order of operations desired, since it is definitely destructive. Also, you don't want -
, as that is dedup
((-string).insert(3, 'baz')
results in a FrozenError). Maybe you were thinking of +string
instead of -string
, but if string
is mutable, that doesn't make a copy, so it becomes a destructive operation. The initial suggestion of string.dup.insert(3, 'baz')
makes the most sense.
In terms of the feature request, I'm against adding such a method. The need for it seems uncommon, and it is easy to use dup
to handle it when it is needed.
Updated by noraj (Alexandre ZANNI) almost 2 years ago
jeremyevans0 (Jeremy Evans) wrote in #note-3:
austin (Austin Ziegler) wrote in #note-2:
In terms of the feature request, I'm against adding such a method. The need for it seems uncommon, and it is easy to use
dup
to handle it when it is needed.
You made a point. Creating non-destructive variant of any destructive method seems unnecessary since there is dup that is pretty easy to use and universal.
Updated by noraj (Alexandre ZANNI) almost 2 years ago
I think we can close this issue.
Updated by jeremyevans0 (Jeremy Evans) almost 2 years ago
- Status changed from Open to Closed