From: Meino Christian Cramer <mccramer@...>
Date: 2003-08-09T16:47:10+09:00
Subject: Ruby and OOP-design (question of an old "procedural person" ;)

Hi !

 I have a newbie question on OOP-design:

 What I have is a large ASCII-File, a list of about 11000 shortwave
 broadcasters. Each line contains the informations about one
 transmitter hold in a long string without any delimiters.

 It is specified, what offsets into a line are to be used to cut off
 the informations one would need about a broadcaster.

 What I want to do is to read the whole file into memory, put each
 information into a sperate "field" to get rid of those
 "information-one-liners"  and then I want to sort the whole thing by
 frequency first and by on-air-time then.

 What I done so far is (pseudo-code):

 --------------------

 class SWFILE( file)
 open the file
 @ist=List.new
 foreach line do
 format line by expressions like @time=line[<start>..<end>]
 transmitter=Broadcaster.new( @freq, @station, @time.....)
 List.append( transmitter )
 end foreach
 end

 class Broadcaster
 def initialize( freq, station, time.....)
  @freq    = freq   
  @station = station
  @time	   = time   
  ...
 end
 end

 class List
  def initialize
   @list=Array.new
  end

  def append( broadcaster)
    @list.push( broadcaster)
  end
 end

 a=SWFILE.new( "<filename>" )

 --------------------


 This works so far....

 Then I read about the new sort_by feature. This is exactly what I
 need!
 
 But sort_by needs an array as input.

 And my "list"-object is an object (or a duck, which quaks ;) holding
 and array...or what...or .... I got confused here.

 Furthermore I am really not sure, whether I have generated as
 "class-ified" program, which is programmed in a procedural way only
 or ... ?

 Two questions:
 What I have to feed where into the structure to sort the broadcasters
 by frequency first and then by on-air-time ?

 Is this "design" ok (in the sense of OOP)?

 Kind regards from a confused duck, which quaks,
 Meino