From: "zverok (Victor Shepelev) via ruby-core" <ruby-core@...>
Date: 2024-05-12T07:57:49+00:00
Subject: [ruby-core:117846] [Ruby master Feature#20484] A new pragma for eager resolution of classes referenced in rescue clauses.

Issue #20484 has been updated by zverok (Victor Shepelev).


Honestly, it is no different than any name used in a branch that wasn���t tested. E.g. if you have this:
```ruby
if foo
  OneClass.new
else
  OtherClass.new
end
```
...and the `else` branch wasn���t covered by tests, and the `OtherClass` isn���t defined, then it will struck in production. The rescue clauses can be seen as kind of ���syntax sugar��� upon this:
```ruby
# ...
rescue => e
  case e
  when SomeClass
    # ...
  when OtherClass
    # ...
  else
    # ...
  end
end
```
Which makes it more obvious that unless you ran into the `rescue` branch, any name inside it wouldn���t be evaluated, and no name errors would be caught.

So the common answer is ���it should be covered by testing and/or static code analysis.��� 

Though theoretically, ���opt-in forced resolution of everything that looks like a module name��� might be an interesting idea to play with (but it probably shouldn���t be limited to `rescue` blocks).

----------------------------------------
Feature #20484: A new pragma for eager resolution of classes referenced in rescue clauses.
https://bugs.ruby-lang.org/issues/20484#change-108252

* Author: jfrisby (Jon Frisby)
* Status: Feedback
----------------------------------------
I've been using Ruby for 20 years, and just today learned (the hard way) that the class name(s) referenced in a `rescue` clause are not resolved until an exception occurs.

Upon reflection, this behavior probably makes sense in a lot of situations.  Late resolution may simplify code loading for the developer.

I would, however, love to see an opt-in feature (a la `frozen-string-literal`) to force resolution when the code is loaded/parsed.



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