From: GOTO Kentaro <gotoken@...>
Date: 2002-07-26T04:53:44+09:00
Subject: Re: [PATCH] object.c ruby.h (fwd)

At Fri, 26 Jul 2002 03:11:02 +0900,
nobu.nokada@softhome.net wrote:
> At Fri, 26 Jul 2002 02:55:28 +0900,
> Dave Thomas wrote:
> > Well, to me, a.true? would imply the same as a == true, which isn't
> > what it does. #to_b, however, implies a conversion to the mythical
> > Boolean type. :)
> 
> Hmmm, then a.t?.  It would be lispy...

Isn't it too hackish :) 

But `?' looks nice because the suffix suggests true-false valued.  As
Dave said, the prefix `to_' would implies conversion to a type.

I vote #truth?.  If someone asks `why not boolean' we can plead that
Boolean algebra is just one of characterizations but not synonym for
the truth value.

---------------------------------------------------------- Object#truth?
     obj.truth? -> true or false
------------------------------------------------------------------------
     Returns a truth-value for this object.  In Ruby, either false or
     nil is regarded as a negative condition.  Everything else is 
     positive one.  `true' is the representative of positive conditions.
        true.truth?       #=> true
        false.truth?      #=> false
        nil.truth?        #=> false
        "string".truth?   #=> true
        0.truth?          #=> true

And #falsity? for symmetry.

-------------------------------------------------------- Object#falsity?
     obj.falsity? -> true or false
------------------------------------------------------------------------
     nagation of Object#truth?.