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NNTP-Posting-Date: Fri, 06 May 2011 01:28:01 -0500
From: Zapanaz <http://joecosby.com/code/mail.pl@foo.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: "Program to an interface" - When to break a design pattern
Date: Thu, 05 May 2011 23:28:26 -0700
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On Thu, 05 May 2011 16:41:33 -0700, Roedy Green
<see_website@mindprod.com.invalid> wrote:

>On Thu, 05 May 2011 12:21:55 -0700, Zapanaz
><http://joecosby.com/code/mail.pl@foo.com> wrote, quoted or indirectly
>quoted someone who said :
>
>>The problem is, where I'm creating sortedMap above, I need the map to
>>retain the insertion order. If what's returned actually is a Map,
>>rather than a LinkedHashMap, then the results the user actually sees
>>are going to be in the wrong order. Making things worse, in this case,
>>nothing would actually break, only the end user would notice anything
>>was actually wrong.
>
>The idea of an interface is you should be able to substitute some
>other implementation and all should work unmodified.  That is not the
>case with the interface you chose.  You need to either find or create
>an interface that nails down all the desired behaviour, or use the
>original actual implementation.
>
>I am not a big fan of this pattern for the following reasons:
>1. it slows down access.
>2. it obfuscates just what the code is using NOW for the
>implementation.
>3. It is more verbose, giving you one more thing you have to eyeball
>carefully and make dance through the genericity hoops. That makes for
>buggier code.
>
>The main place it would pay off is if you plan to later do some fine
>tuning, and want to leave open the option of easily substituting your
>own tuned collection classes.

Thanks Roedy.

Your web page was a lot of help to me when I was learning Java years
ago, thanks for that too.

-- 
Zapanaz
International Satanic Conspiracy
Customer Support Specialist
http://joecosby.com/ 
Isn't round the funny side that never ends?

:: Currently listening to For His Namesake, by Amboy Dukes/Ted Nugent, from "Journey to the Center of the Mind"