From: "byroot (Jean Boussier) via ruby-core" <ruby-core@ml.ruby-lang.org>
To: ruby-core@ml.ruby-lang.org
Cc: "byroot (Jean Boussier)" <noreply@ruby-lang.org>
Subject: [ruby-core:117595] [Ruby master Misc#20434] Deprecate encoding-releated regular expression modifiers
Date: Thu, 18 Apr 2024 09:23:44 +0000 (UTC) [thread overview]
Message-ID: <redmine.journal-107997.20240418092343.10206@ruby-lang.org> (raw)
In-Reply-To: redmine.issue-20434.20240417155807.10206@ruby-lang.org
Issue #20434 has been updated by byroot (Jean Boussier).
`/\x81\x40/.force_encoding("Windows-31J")` wouldn't work because `String#force_encoding` mutates the string, and Regexp literals are immutable.
Similarly `String#encode` doesn't just change the string encoding attribute, but convert the bytes to the new encoding. So I'd expect `/\3000/.encode("Windows-31J")` to fail with:
```ruby
\x81" on UTF-8 (Encoding::InvalidByteSequenceError)
```
So I think the String API to mirror would be `String.new(encoding:)`
- `Regexp.new(/\x81\x40/, encoding: Encoding::WINDOWS_31J)`
- `Regexp.new("\x81\x40", encoding: Encoding::WINDOWS_31J)`
But if we want an instance method, I think something like:
`/\x81\x40/.encoded(Encoding::WINDOWS_31J)`, which by the way would also be useful on `String`, e.g., this is common:
```ruby
# frozen_string_literal: true
THING = "fée".dup.force_encoding(Encoding::ISO8859_1)
```
So it could become:
```ruby
# frozen_string_literal: true
THING = "fée".encoded(Encoding::ISO8859_1)
```
----------------------------------------
Misc #20434: Deprecate encoding-releated regular expression modifiers
https://bugs.ruby-lang.org/issues/20434#change-107997
* Author: kddnewton (Kevin Newton)
* Status: Open
----------------------------------------
This is a follow-up to @duerst's comment here: https://bugs.ruby-lang.org/issues/20406#note-6.
As noted in the other issue, there are many encodings that factor in to how a regular expression operates. This includes:
* The encoding of the file
* The encoding of the string parts within the regular expression
* The regular expression encoding modifiers
* The encoding of the string being matched
At the time the modifiers were introduced, I believe the modifiers may have been the only (??) encoding that factored in here. At this point, however, they can lead to quite a bit of confusion, as noted in the other ticket.
I would like to propose to deprecate the regular expression encoding modifiers. Instead, we could suggest in a warning to instead create a regular expression with an encoded string. For example, when we find:
```ruby
/\x81\x40/s
```
we would instead suggest:
```ruby
::Regexp.new(::String.new("\x81\x40", encoding: "Windows-31J"))
```
or equivalent. As a migration path, we could do the following:
1. Emit a warning to change to the suggested expression
2. Change the compiler to compile to the suggested expression when those flags are found
3. Remove support for the flags
Step 2 may be unnecessary depending on how long of a timeline we would like to provide. To be clear, I'm not advocating for any particular timeline, and would be fine with this being multiple years/versions to give plenty of time for people to migrate. But I do think this would be a good change to eliminate confusion about the interaction between the four different encodings at play.
--
https://bugs.ruby-lang.org/
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next prev parent reply other threads:[~2024-04-18 9:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-17 15:58 [ruby-core:117568] [Ruby master Misc#20434] Deprecate regular expression modifiers kddnewton (Kevin Newton) via ruby-core
2024-04-18 0:23 ` [ruby-core:117581] [Ruby master Misc#20434] Deprecate encoding-releated " shyouhei (Shyouhei Urabe) via ruby-core
2024-04-18 6:22 ` [ruby-core:117591] " duerst via ruby-core
2024-04-18 9:23 ` byroot (Jean Boussier) via ruby-core [this message]
2024-04-18 11:41 ` [ruby-core:117596] [Ruby master Misc#20434] Deprecate encoding-related " Eregon (Benoit Daloze) via ruby-core
2024-04-18 18:50 ` [ruby-core:117600] " kddnewton (Kevin Newton) via ruby-core
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