From: "noraj (Alexandre ZANNI) via ruby-core" <ruby-core@...>
Date: 2023-01-02T23:52:19+00:00
Subject: [ruby-core:111586] [Ruby master Feature#14919] Add String#byteinsert

Issue #14919 has been updated by noraj (Alexandre ZANNI).





Yes a grapheme can be composed of several code points.



An example is variant selector:



```ruby

irb(main):001:0> a = "\u2665\n\u2764\n\u2665\ufe0f\n\u2764\ufe0f"

=> "���\n���\n������\n������"

irb(main):002:0> puts a

���

���                                                

������                                               

������                                               

=> nil                                           

irb(main):003:0> a.chars

=> ["���", "\n", "���", "\n", "���", "���", "\n", "���", "���"]

```



But fortunately, in Ruby, string indices are already mapping characters and not graphemes. So has Martin highlighted, `String#[]=` already cover all use cases I can think of.



```ruby

irb(main):007:0> r = "I \u2665 Ruby!"

=> "I ��� Ruby!"

irb(main):009:0> r[2] = "\u2764\ufe0f"

=> "������"

irb(main):010:0> r

=> "I ������ Ruby!"

```



The only thing I could think of `String#byteinsert` would be to directly mess with UTF-8 encoding to forge invalid encoding on purpose. But such a use case is rare and advanced and so can maybe be handled with pack and unpack rather than creating a new byteinsert method?



```

irb(main):014:0> r.unpack1('a*')

=> "I \xE2\x9D\xA4\xEF\xB8\x8F Ruby!"

```



@aycabta Maybe you could give me a handy example of the usage of `String#byteinsert` I can't think of?



----------------------------------------

Feature #14919: Add String#byteinsert

https://bugs.ruby-lang.org/issues/14919#change-100956



* Author: aycabta (aycabta .)

* Status: Open

* Priority: Normal

----------------------------------------

It's important for multibyte String editing. Unicode grapheme characters sometimes have plural code points. In text editing, software sometimes should add a new code point to an existing grapheme character. String#byteinsert is important for it.



I implemented by pure Ruby in my code.

https://github.com/aycabta/reline/blob/b17e5fd61092adfd7e87d576301e4e19a4d9e6d8/lib/reline/line_editor.rb#L255-L260









-- 

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

 ______________________________________________
 ruby-core mailing list -- ruby-core@ml.ruby-lang.org
 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
 ruby-core info -- https://ml.ruby-lang.org/mailman3/postorius/lists/ruby-core.ml.ruby-lang.org/