From: "ufuk (Ufuk Kayserilioglu) via ruby-core" <ruby-core@...>
Date: 2025-02-27T00:04:16+00:00
Subject: [ruby-core:121185] [Ruby master Feature#21160] Local return from proc

Issue #21160 has been updated by ufuk (Ufuk Kayserilioglu).


`next` isn't necessarily the correct thing to use here, `break` is:
```ruby
foo = fulfills_promise :generate_large_image do |image_data|
  break false if image_data.nil?

  puts 'Saving image..'
  # etc.
end

foo #=> false
```

And the name exactly conveys the concept of breaking out of the block, in my opinion.

For example:
```ruby
result = (1..100).each do |num|
  break num if num > 3
  puts num
end

puts "Got result #{result}"
```
will print
```
1
2
3
Got result 4

----------------------------------------
Feature #21160: Local return from proc
https://bugs.ruby-lang.org/issues/21160#change-112120

* 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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