From: "byroot (Jean Boussier) via ruby-core" <ruby-core@...>
Date: 2025-08-29T07:16:40+00:00
Subject: [ruby-core:123117] [Ruby Feature#21555] Add support for predicate attribute reader names

Issue #21555 has been updated by byroot (Jean Boussier).


> This feature is only supported for attr_reader and attr, not attr_writer or attr_accessor, since setter methods cannot have question marks.

Using the same logic, `attr_accessor :enabled?` could generate `#enabled?` and `#enabled=` without problem. `attr_writer :enabled?` would be weird though.

----------------------------------------
Feature #21555: Add support for predicate attribute reader names
https://bugs.ruby-lang.org/issues/21555#change-114435

* Author: shan (Shannon Skipper)
* Status: Open
----------------------------------------
After manually aliasing predicate methods many times, I wanted to propose letting `attr_reader` take predicate method names that correspond to instance variables of the base name without a trailing question mark. https://github.com/ruby/ruby/pull/14391

If the base name method doesn't already exist, a predicate name defines a base name method attribute reader to alias then undefines the base name.

For example, this creates an `enabled?` method that reads `@enabled`:
```ruby
attr_reader :enabled?
```

This feature is only supported for `attr_reader` and `attr`, not `attr_writer` or `attr_accessor`, since setter methods cannot have question marks.

Example:
```ruby
class Example
  attr_reader :valid?, :meaning

  def initialize
    @valid = [true, false].sample
    @meaning = 42
  end
end

Example.new.valid? #=> true
```



-- 
https://bugs.ruby-lang.org/
______________________________________________
 ruby-core mailing list -- ruby-core@ml.ruby-lang.org
 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
 ruby-core info -- https://ml.ruby-lang.org/mailman3/lists/ruby-core.ml.ruby-lang.org/