From: Robert Dober <robert.dober@...>
Date: 2006-09-20T19:59:10+09:00
Subject: Re: Something strange in ruby or I'm a newbie?

------=_Part_169556_30934447.1158749947531
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: quoted-printable
Content-Disposition: inline

On 9/20/06, Hussachai Puripunpinyo <siberhus@hotmail.com> wrote:
>
> Question 2:
>
> nil in ruby can put in condition statement
> such as if(nil) it will assume that's false
>
> ex.
> if(nil)
> else
>   puts "nil is false"
> end
>
> sure it show me the string
> Becuase I'm curious,I want to test more
>
> puts nil=3D=3Dnil #Yeah that's true
>
> puts !nil #true
>
> puts !nil=3D=3Dtrue #true
>
> puts nil=3D=3Dfalse #FALSE !!!
>
> What happen in the last statement? [or I miss something]


That is a very interesting way you are looking at things, I would not
necessarily  think Ruby's behavior as bad.
For myself I think rubies semantics can be expressed as follows

class Object
    def true?
        true
    end
end

class NilClass
    def true?
        false.true?
    end
end

class FalseClass
    def true?
        self
    end
end


p true.true?
p "".true?
p nil.true?

Now - in the classical terms of thinking you have invoked above, if an
object evaluates to true or false just replace it by #true?. (you can
imagine the interpreter doing that e.g.)

You see somehow comparing
nil =3D=3D false does not make too much sense in that context, as an analog=
y you
have

puts "42 is true" if 42
puts "42**2 is true 2" if 1764
and yet
42 =3D=3D 1764 =3D> false ;)

Cheers
Robert

> --
> Posted via http://www.ruby-forum.com/.
>
>


--=20
Deux choses sont infinies : l'univers et la b=EAtise humaine ; en ce qui
concerne l'univers, je n'en ai pas acquis la certitude absolue.

- Albert Einstein

------=_Part_169556_30934447.1158749947531--