[ruby-core:121188] [Ruby master Feature#21160] Local return from proc

Issue #21160 has been updated by nobu (Nobuyoshi Nakada).


Why not rescue `LocalJumpError`?

```ruby
  def self.fulfill_promise(promise_name, data)
    puts "Fulfilling promise: #{promise_name}"

    callback = @@promise_callbacks[promise_name]

    begin
      complete = callback.call(data)
    rescue LocalJumpError => e
      complete = e.exit_value
    end
    if complete
      puts 'Complete!'
    else
      puts 'Failed!'
    end
  end
```

This works with both of `return` and `break` in already released versions of Ruby, and even your DSL does not need to change.
If we were add a new keyword, you would have to wait for the end of this year at least.

----------------------------------------
Feature #21160: Local return from proc
https://bugs.ruby-lang.org/issues/21160#change-112123

* Author: JustJosh (Joshua Stowers)
* Status: Open
----------------------------------------
When writing DSL-style helper methods, I often store block arguments as procs to use as callbacks.
Using `return` in a proc will return from the context it was created in, which is unsuitable in the following example.
Since procs cannot be converted to lambdas, I end up using `next` to return a value from them early.

Example:
``` ruby
fulfills_promise :generate_large_image do |image_data|
  next false if image_data.nil?

  puts 'Saving image..'
  # etc.
end
```

This works but confuses most readers.

I propose introducing an alias for it that is more appropriate for this use case.
Perhaps `pass` or `continue`?

It's worth noting that `return` would work with `fulfills_promise :foo, -> (bar) do`, though it detracts a bit from a DSL's expressiveness.




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