[ruby-core:114494] [Ruby master Bug#19784] String#delete_prefix! problem
From:
"Eregon (Benoit Daloze) via ruby-core" <ruby-core@...>
Date:
2023-08-24 15:08:28 UTC
List:
ruby-core #114494
Issue #19784 has been updated by Eregon (Benoit Daloze).
mame (Yusuke Endoh) wrote in #note-5:
> Note that encoding validity is checked on a position-by-position basis:
That's not clear to me.
Do you mean that if the argument or if the receiver String is not `String#valid_encoding?`, then we compare byte-by-byte, and otherwise we compare character-by-character ?
I think we should not consider whether a given substring is valid, that would be very expensive to check.
I wonder if always comparing byte-by-byte for both is not a lot simpler, faster, and also what most users expect.
And of course still have the encoding check to ensure both strings have a compatible encoding.
----------------------------------------
Bug #19784: String#delete_prefix! problem
https://bugs.ruby-lang.org/issues/19784#change-104279
* Author: inversion (Yura Babak)
* Status: Open
* Priority: Normal
* ruby -v: ruby 3.2.2 (2023-03-30 revision e51014f9c0) [x86_64-linux]
* Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
Here is the snipped and the question is in the comments:
``` ruby
fp = 'with_BOM_16.txt'
body = File.read(fp).force_encoding('UTF-8')
p body # "\xFF\xFE1\u00001\u0000"
p body.start_with?("\xFF\xFE") # true
body.delete_prefix!("\xFF\xFE") # !!! why doesn't work?
p body # "\xFF\xFE1\u00001\u0000"
p body.start_with?("\xFF\xFE") # true
body[0, 2] = ''
p body # "1\u00001\u0000"
p body.start_with?("\xFF\xFE") # false
```
Works same
on Linux (ruby 3.2.2 (2023-03-30 revision e51014f9c0) [x86_64-linux])
and Windows (ruby 3.2.2 (2023-03-30 revision e51014f9c0) [x64-mingw-ucrt])
--
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