From: Yukihiro Matsumoto <matz@...>
Date: 2013-03-27T21:52:44+09:00
Subject: Re: Why don't TrueClass and FalseClass share a common Boolean ancestor

Hi,

There's nothing true and false commonly share, thus no Boolean class.
Besides that, in Ruby, everything behave as Boolean value, as Xavier
mentioned in [ruby-talk:406208].

							matz.

In message "Re: Why don't TrueClass and FalseClass share a common Boolean ancestor"
    on Wed, 27 Mar 2013 20:56:24 +0900, "Rob N." <lists@ruby-forum.com> writes:

|Both TrueClass and FalseClass inherit directly from the Object class.
|They share a common structure and do very similar jobs. So why don't
|they share a common parent between them and Object? BooleanClass
|perhaps?
|
|I wanted to test some input for true or false and thought
|true.class.ancestors and false.class.ancestors would give me a shared
|parent class to test for rather than have to check for each
|independently.
|
|An academic question really, that piqued my curiosity and seemed more
|strange the deeper I looked. It got me looking into the C code behind
|Ruby for the first time (which can't be a bad thing), where I was struck
|by the similarities between the two object structures.
|
|From the positioning of the comments*:
|
|TrueClass methods appear to be defined by:
|
|  true_to_s, true_and, true_or, true_xor.
|
|FalseClass methods appear to be defined by:
|
|  false_to_s, false_and, false_or, false_xor
|
|Then there are some other methods that seem to be hung on the end and I
|assume from the names are associated with the core ruby space:
|
|  rb_true, rb_false, rb_obj_match, rb_obj_not_match, rb_obj_cmp
|
|Which look ripe to be placed within a BooleanClass name space to me.
|
|Looking at https://github.com/ruby/ruby/blob/trunk/object.c lines 1107
|to 1342.
|
|So just wondered if anyone knew why there isn't a dedicated parent class
|to TrueClass and FalseClass.
|
|-------------------
|* My knowledge of C is non-existent, so please excuse any fundamental
|misunderstanding of the code that I may have made. For example, I'm
|failing to find where Qtrue and Qfalse are defined, and both seem to
|hold the key to understanding true and false within the ruby code.
|
|-- 
|Posted via http://www.ruby-forum.com/.