From: Malte Milatz <malteDELETETHIS@...>
Date: 2004-06-27T23:33:02+09:00
Subject: Re: Newbie: How to model this?

Ralph Aichinger wrote:
> class Location
>  def initialize(lon,lat,hgt)
>    @lon = lon
>    @lat = lat
>    @hgt = hgt
>  end
> end
> 
> I want methods like myPoint.dmsdegrees giving just the degrees
> part of myPoint in degree, minute, second format. These should be
> "virtual attributes" if I understand Thomas/Hunt right.
> 
> How can I define this in the most elegant fashion? I cannot let Location
> inherit this from a base class "Angle" with all these conversion
> methods, can I, because a Location is not a Angle, at least not just
> a Angle.

I would do it like this (or similar):

    class Location
        attr_accessor :lon, :lat, :hgt
        def initialize(lon,lat,hgt)
            @lon = DegreeValue.new(lon)
            @lat = DegreeValue.new(lat)
            @hgt = FootValue.new(hgt)
        end
    end

    class DegreeValue < Float
        def dms
            # Some calculation
            [ degrees, minutes, seconds ]
        end
    end

Alternatively you could add Numeric#dms.

-- 
My email address is malte at gmx-topmail.de