From: "byroot (Jean Boussier) via ruby-core" <ruby-core@...>
Date: 2026-08-10T06:53:24+00:00
Subject: [ruby-core:126356] [Ruby Feature#22238] String#tr to take a Hash for multi-character replacements

Issue #22238 has been reported by byroot (Jean Boussier).

----------------------------------------
Feature #22238: String#tr to take a Hash for multi-character replacements
https://bugs.ruby-lang.org/issues/22238

* Author: byroot (Jean Boussier)
* Status: Open
----------------------------------------
This is @matz's counter proposal to [Feature #22229] from the last dev-meeting

> matz: I will counter-propose String#tr-with-hash style.

```ruby
'Hello </script>'.tr(">" => '\u003e', "<" => '\u003c', "&" => '\u0026') # matz: OK

'Hello </script>'.tr("abc" => 'ABC') # should raise an exception
'Hello </script>'.tr("abc" => 'ABC', "ab" => "XY") # should raise an exception

"f��e".tr("��" => "���") # it should work

"Hello".tr("l" => "ABC", "o" => "XYZ") #=> "HeABCABCXYZ"

"Hello".gsub(/./m) { hash[$&] || $& } # gsub equivalent
```

Notes:

- Hash keys MUST be single characters (but can be multi-byte).
- Values can be multiple characters.



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