Issue #14313 has been updated by kou (Kouhei Sutou).
`Kernel.#raise` expects backtrace for the 3rd argument.
If we want to extend the current `Kernel.#raise` behavior, we should create a new issue instead of discussing in this issue.
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Feature #14313: Support creating KeyError with receiver and key from Ruby
https://bugs.ruby-lang.org/issues/14313#change-69397
* Author: kou (Kouhei Sutou)
* Status: Open
* Priority: Normal
* Assignee: matz (Yukihiro Matsumoto)
* Target version:
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`KeyError` has readers for error details, `receiver` and `key`. They are convenient to process `KeyError`.
We can set `receiver` and `key` to `KeyError` by `rb_key_err_new()` in C. But we can't set them in Ruby. Because `receiver` and `key` use no `@` instance variables.
How about adding `KeyError#initialize` that accepts `receiver` and `key`? Because `KeyError` is useful in pure Ruby libraries. For example, csv library uses `KeyError`: https://svn.ruby-lang.org/cgi-bin/viewvc.cgi/trunk/lib/csv.rb?revision=59849&view=markup#l321
```ruby
def fetch(header, *varargs)
# ...
raise KeyError, "key not found: #{header}"
# ...
end
```
I want to use `KeyError` for `Hash` like objects such as `Arrow::Table` in [Red Arrow](https://github.com/red-data-tools/red-arrow/).
The attached patch adds `KeyError#initialize` that behaves as the following:
```ruby
p KeyError.new.message
# => "KeyError": No change. Keep backward compatibility.
p KeyError.new("Message").message
# => "Message": No change. Keep backward compatibility.
p KeyError.new(receiver: Object.new).receiver
# => The Object instance.
p KeyError.new(key: :unknown_key).key
# => :unknown_key
key_error = KeyError.new(receiver: Object.new, key: :unknown_key)
p key_error.receiver
# => The Object instance.
p key_error.key
# => :unknown_key
key_error = KeyError.new("Message", receiver: Object.new, key: :unknown_key)
p key_error.message
# => "Message"
p key_error.receiver
# => The Object instance.
p key_error.key
# => :unknown_key
```
---Files--------------------------------
key_error_new.diff (2.91 KB)
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