From: marcandre-ruby-core@...
Date: 2020-07-02T20:15:46+00:00
Subject: [ruby-core:99038] [Ruby master Feature#17004] Provide a way for methods to omit their return value

Issue #17004 has been updated by marcandre (Marc-Andre Lafortune).


jeremyevans0 (Jeremy Evans) wrote in #note-13:
> Due to Sequel::Dataset#insert's flexible API, it would be hard to support this as a method argument.

Seems to be that a better API for this is using a block parameter.

```ruby
# need the ID:
insert(...) do |last_inserted_id|
  # ...
end

# don't need the ID:
insert(...)
```

Another possibility is to implement a lazy return value, something like:

```ruby
class LazyID
  def to_i
    # get the ID
  end
end

def insert(...)
  # ...
  LazyID.new(self)
end
```

I remain unconvinced the proposal is a good idea.

----------------------------------------
Feature #17004: Provide a way for methods to omit their return value
https://bugs.ruby-lang.org/issues/17004#change-86413

* Author: shyouhei (Shyouhei Urabe)
* Status: Open
* Priority: Normal
----------------------------------------
In ruby, it often is the case for a method's return value to not be used by its caller.  Even when a method returns something meaningful, its caller is free to ignore it.

Why not provide a way for a method to know if its return value is needed or not?  That adds a room for methods to be optimized, by for instance skipping creation of complex return values.

The following pull request implements `RubyVM.return_value_is_used?` method, which does that: https://github.com/ruby/ruby/pull/3271



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