From: Dan Doel <djd15@...>
Date: 2003-12-18T17:14:02+09:00
Subject: Re: Newbie questions

Jim Frapper wrote:

>- The ability to overload constructors.
>  
>
The way multiple constructors should probably be done in Ruby is similar 
to the
way people do it in Smalltalk.  For example, if you're modeling a 
mathematical
plane in Smalltalk, you might define the following constructors:

withPoint: p1 withPoint: p2 withPoint: p3

withPoint: p withNormalVector: n

doing:

plane <- Plane new

Would just make a default plane with no instance variables set, while

plane <- Plane withPoint: point1 withNormalVector: vector

Would make a fully qualified plane.

Analogues in Ruby would go something like:

class Plane
    def Plane.fromPoints(p1, p2, p3)
       ...
    end

    def Plane.fromPointAndNormal(p, n)
       ...
    end
end

There's nothing special about #new that means it's the only thing you're
allowed to call a constructor (or that you need to allow it to be a public
constructor at all. In the above example, you'd probably want to make it
private).  All you need to do is possibly broaden your
definition of constructor a bit.

- Dan