From: Robert Klemme <shortcutter@...>
Date: 2009-05-06T23:30:48+09:00
Subject: Re: Design question

2009/5/6 Srijayanth Sridhar <srijayanth@gmail.com>:
> I am building a simple tool to help with some statistical analysis of a
> sports site. I have the following:
>
> class Player # just a wrapper around ostruct for read_only access
> class Team # a collection of players
> class League # a collection of teams
>
> There are many ways I can "build" the league so to speak. I want to be able
> to build the league from a web site(scraping for information), from a DB(for
> local access) and a file(for even more local access I suppose). Now I am
> having a bit of a problem organizing a few things.
>
> Should I have an abstract class Builder and derive WebBuilder, DBBuilder,
> and FileBuilder from it or should I just have different methods within the
> league class?

Definitively decouple the stuff into several other classes and do not
do it with a bunch of methods!

> If I were to make these separate classes, then the builder
> class will have to somehow get the data back across to the League class
> which actually builds the team. It feels a bit kludgy. I don't want to
> burden the Team and Player's constructors with any more than just basic
> assignments. Is this a bad idea?
>
> And the bigger fish here is the web builder. The web builder has to screen
> scrape a site with a list of teams, from which it goes to each team page,
> and further fetches statistics by going to the player's site. Its really
> elementary to do, but again, where should it ideally fit?

From what you write I conclude (although not 100% sure) that you have
read only access to all the data storage variants (at least for web
this sounds reasonable).  This is certainly a point that needs
clarification.

Note, I haven't used ActiveRecord so far but I would probably use that
(or any other OO mapper) to do the DB binding.  Then I'd try to model
the file and web bindings with a similar interface.  Dunno whether
this is feasible but at least worth exploring.

Kind regards

robert

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