> > On Nov 14, 2011, at 10:54 AM, Jos=E9 Francisco Calvo Moreno wrote: > > > About to add this method to Fixnum, Integer or Numeric you must excuse > me because I'm starting to understand the Ruby Core. I though that Fixnum > is the base of Integer number and adding a C function to it will solve th= e > problem and make the condition faster. About the zero condition, I have m= y > doubts but maybe a solution would be return nil. > > 1.positive? =3D> true > > -1.positive? =3D> false > > 0.positive? =3D> nil (same as false) > > That may break the Principle of Least Surprise for methods ending in a > question mark. In Ruby, nil and false are equivalent for the purposes of > failing a boolean test. The expectation for a method ending in ? is binar= y; > that is, either true or false. There is *no* third possible condition by > tradition. > > A user should not be expected to differentiate between a ? method > returning nil and a method returning false. > > IMHO. > > cr > > > --000325556062af0c6704b1b56ca5 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Hi Chuck,

You are right, totally right. =A0I have been t= hinking about it and I believe that the best solutions is as follow:

<= div>

=A01.positive? =3D> true

-1.positive? =3D&g= t; false

=A01.negative? =3D> false

-1.negative? =3D= > true

=A00.positive? =3D> false

= =A00.negative? =3D> false

About zero as you can= read at Wikipedia (http://en.wikipedia.org/wiki/Positive_number) "The number=A0zero=A0is neither positive nor negative, = and therefore has no sign", for this reason I think that best solution= is to return false in all cases with positive? and negative? when number i= s zero. With this solution you are respecting at the same time=A0the= Principle of Least Surprise=A0with methods ending in question mark and the= no sign nature of zero number.

The only problem that I see is that

=A0not 0.positive? =3D> true

could be con= fusing and you may think that 0 is negative (when it is not).

2011/11/14 Chuck Remes <cremes.devlist@mac.com>

On Nov 14, 2011, at 10:54 AM, Jos=E9 Francisco Calvo Moreno wrote:

> About to add this method to Fixnum, Integer or Numeric you must excuse= me because I'm starting to understand the Ruby Core. I though that Fix= num is the base of Integer number and adding a C function to it will solve = the problem and make the condition faster. About the zero condition, I have= my doubts but maybe a solution would be return nil.

1.positive? =3D> true

-1.positive? =3D> false

0.positive? =3D> nil (same as false)

That may break the Principle of Least Surprise for methods ending in a ques= tion mark. In Ruby, nil and false are equivalent for the purposes of failin= g a boolean test. The expectation for a method ending in ? is binary; that = is, either true or false. There is *no* third possible condition by traditi= on.

A user should not be expected to differentiate between a ? method returning= nil and a method returning false.

IMHO.

cr

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