[Chicago-talk] Object question - subclass or make two similarclasses

Jay Strauss me at heyjay.com
Sun Feb 1 14:31:24 CST 2004


I get it

Thanks
Jay
----- Original Message -----
From: "Steven Lembark" <lembark at wrkhors.com>
To: "Chicago.pm chatter" <chicago-talk at mail.pm.org>
Sent: Sunday, February 01, 2004 11:41 AM
Subject: Re: [Chicago-talk] Object question - subclass or make two
similarclasses


>
>
> -- Jay Strauss <me at heyjay.com>
>
> > Hi,
> >
> > I have 2 classes that have identical methods.  Should I write 2 classes,
> > or a parent and 2 subclasses?  The class is "brokerage" as in Ameritrade
> > and InteractiveBrokers.  They both have methods like: connect,
placeOrder,
> > getQuote, getTransactionHistory... but the code to perform these actions
> > is totally different between classes.
> >
> > I'm just wondering, what do I gain by making a single parent, and
> > subclassing?
>
> What you probably want is a generic (a.k.a. 'virtual') base
> class called "brokerage" that defines the generic methods.
> That puts most of your boilerplate in one place.
>
> The derived classes can then supply their own methods to
> modify behavior in the base class if necessary. Careful
> use of data in the derived classes will probably leave the
> base class doing all the work, or at least most of it.
>
> For example, supplying callbacks in the class data might
> allow a generic "place an order" method to deal with the
> variety between brokerage houses.
>
> Advantages are not having to hack the code in multiple
> places to fix/extend it and less work the next time you
> have to add a brokerage (i.e., reusability).
>
>
>
>
> --
> Steven Lembark                               2930 W. Palmer
> Workhorse Computing                       Chicago, IL 60647
>                                             +1 888 359 3508
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>




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