From: "palkan (Vladimir Dementyev) via ruby-core" <ruby-core@...>
Date: 2024-01-10T22:32:22+00:00
Subject: [ruby-core:116161] [Ruby master Feature#20164] Add Exception#deconstruct_keys

Issue #20164 has been updated by palkan (Vladimir Dementyev).


+1 for making exceptions pattern-matching friendly. The example above demonstrates the use case pretty well (class + message matching).

The question is what keys must be supported for each standard exception class? The plain Ruby implementation could be as follows:

```ruby
class Exception
  # Not sure if we need to take into account the `keys` argument
  def deconstruct_keys(*) = {message:, cause:}
end

class NameError
  def deconstruct_keys(*) = super.merge(name:)
end
```

----------------------------------------
Feature #20164: Add Exception#deconstruct_keys
https://bugs.ruby-lang.org/issues/20164#change-106167

* Author: Dan0042 (Daniel DeLorme)
* Status: Open
* Priority: Normal
----------------------------------------
It would be convenient to perform pattern matching with exception classes. So `Exception#deconstruct_keys` should return a hash with `:message` (original_message) as well as any other keys specific to the exception subclass.

Examples:
```
begin
  #code
rescue => err
  case err
  in StandardError(message: /Permission denied/) 
    abort "please select a different file"
  in NameError(name: :foo)
    retry if require "foo_helper
  else
    raise
  end
end
```



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