[ruby-core:119263] [Ruby master Feature#20756] Introduce Boolean class

["matz (Yukihiro Matsumoto) via ruby-core" <ruby-core@ml.ruby-lang.org>]

Issue #20756 has been updated by matz (Yukihiro Matsumoto).

Status changed from Open to Rejected

#12515 is an enough reason to reject this idea.



> Rejected for several reasons:
>
> * many gems and libraries had already introduced Boolean class. I don't want to break them.
> * true and false are the only representative of true-false values. In Ruby. nil and false are falsy values, and everything else is a true value. There's no meaning for having a superclass of TrueClass and FalseClass as Boolean.

Even if we introduced `Boolean` class, it'd only used to check type/class using `kind_of?` (which is against duck-typing principle). Since we have no common behavior/implementation of boolean objects.

Matz.


----------------------------------------
Feature #20756: Introduce Boolean class
https://bugs.ruby-lang.org/issues/20756#change-109857

* Author: kbrock (Keenan Brock)
* Status: Rejected
----------------------------------------
Hello All,

Is is possible to add a parent class for `TrueClass` and `FalseClass`?
I always found it strange that there was not a concept to group `true` and `false` together.

e.g.:

```ruby
class TrueClass  < Boolean ; end
class FalseClass < Boolean ; end

# replaces the hack:
module Boolean ; end
TrueClass.include(Boolean);
FalseClass.include(Boolean);

```

In our code, we often want to validate that a value is of a certain type.

```ruby
case(value)
when String  ...
when Integer ...
when true, false ... # Boolean
# alt: when TrueClass, FalseClass 
end

# or

def valid_args?
  value.kind_of?(String)
end
def valid_args?
  value.kind_of?(Integer)
end
def valid_args?
  [true, false].include?(value)
  [TrueClass, FalseClass].detect { |klass| value.kind_of?(klass) }
end
```

Does it make sense to others to have a way to group `true` and `false` together?

Thank you for your thoughts,
Keenan



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