[ruby-core:77840] [Ruby trunk Feature#12515] Create "Boolean" superclass of TrueClass / FalseClass

Issue #12515 has been updated by Rodrigo Rosenfeld Rosas.


I'd just like to add a real situation where I missed a Boolean class recently.

A web request takes an array of values in a JSON encoded string and before processing the data the server-side handler will try to validate the input by comparing the elements type. If Boolean existed, the validation rule would be something like:

~~~
input = JSON.parse(params['value'])
raise InvalidInput, 'size must be 6' unless input.size == 6
raise InvalidInput, "types don't match" unless input.map(&:class) ==
  [String, String, String, Boolean, String, Boolean]
~~~

As you can imagine, the validation took more effort without the existence of Boolean. Something like:

~~~
input.map{|x| x == false || x == true ? :boolean : x.class } ==
  [String, String, String, :boolean, String, :boolean]
~~~

----------------------------------------
Feature #12515: Create "Boolean" superclass of TrueClass / FalseClass
https://bugs.ruby-lang.org/issues/12515#change-61150

* Author: Loren Segal
* Status: Rejected
* Priority: Normal
* Assignee: 
----------------------------------------
Since Ruby 2.4 is unifying Bignum/Fixnum into Integer (https://bugs.ruby-lang.org/issues/12005), it seems reasonable to do something similar for TrueClass / FalseClass, and create a proper Boolean hierarchy. The implementation would be fairly straightforward and should be back compat unless someone already has a "Boolean" class at toplevel out there.

Given the compatibility implications of Integer, this Boolean proposal is even less intrusive.

Sample implementation:

~~~
class Boolean < BasicObject; end
class TrueClass < Boolean; end
class FalseClass < Boolean; end
~~~




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