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Groups > comp.lang.java.programmer > #2915

Re: calling own methods from constructor

Newsgroups comp.lang.java.programmer
From Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at>
Subject Re: calling own methods from constructor
References <slrnippkd9.phi.avl@gamma.logic.tuwien.ac.at> <alpine.DEB.2.00.1104062255160.1512@urchin.earth.li>
Message-ID <slrnipqtt1.phi.avl@gamma.logic.tuwien.ac.at> (permalink)
Date 2011-04-07 08:36 +0000

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Tom Anderson <twic@urchin.earth.li> wrote:
> On Wed, 6 Apr 2011, Andreas Leitgeb wrote:
>> Is there any *good* use of having the constructor call a method that 
>> actually *can* be overridden in a subclass? I mean, are there 
>> (non-anti)patterns of explicitly allowing subclasses to hook into 
>> base-class's construction?

> public abstract class Library {
>  	private List<Document> documents;
>  	protected Library() {
>  		documents = new ArrayList<Document>();
>  		Collection<String> titles = listDocuments();
>  		for (String title: titles) {
>  			Document doc = loadDocument(title);
>  			// do other preparatory stuff with the document
>  			documents.add(doc);
>  		}
>  	}
>  	protected abstract Collection<String> listDocuments();
>  	protected abstract Document loadDocument(String title);
> }
>
> public class FilesystemLibrary extends Library {
>  	// ...
> }
> [...]

Sorry, in my eyes, this is one of the anti-patterns.

> What are the alternatives?

It's hard to speculate about alternatives for an artificial example.

I'd say, that they exist for any reasonable specification of the problem,
and "back it up"(*) by declaring specifications for which no (or only
mindboggingly contrived) alternatives exist as unreasonable ;-)

(*): In German, we use double-quotes also to indicate tongue-in-cheek
formulations that aren't to be taken entirely literally/serious.
I've recently learned that they are not always thusly understood,
elsewhere.  Therefore this explanation. Is there any common markup
for it that would be recognized in the English-speaking world?

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Thread

calling own methods from constructor Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-04-06 20:48 +0000
  Re: calling own methods from constructor Tom Anderson <twic@urchin.earth.li> - 2011-04-06 23:06 +0100
    Re: calling own methods from constructor Lew <noone@lewscanon.com> - 2011-04-06 18:24 -0400
      Re: calling own methods from constructor Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-04-07 08:44 +0000
        Re: calling own methods from constructor Robert Klemme <shortcutter@googlemail.com> - 2011-04-07 04:14 -0700
          Re: calling own methods from constructor Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-04-07 12:32 +0000
            Re: calling own methods from constructor Robert Klemme <shortcutter@googlemail.com> - 2011-04-07 05:55 -0700
            Re: calling own methods from constructor Lew <lew@lewscanon.com> - 2011-04-07 08:10 -0700
              Re: calling own methods from constructor Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-04-07 20:31 +0000
                Re: calling own methods from constructor Lew <lew@lewscanon.com> - 2011-04-07 14:10 -0700
                Re: calling own methods from constructor Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-04-07 22:15 +0000
                Re: calling own methods from constructor Lew <noone@lewscanon.com> - 2011-04-07 21:22 -0400
              Re: calling own methods from constructor Tom Anderson <twic@urchin.earth.li> - 2011-04-07 23:08 +0100
                Re: calling own methods from constructor Lew <noone@lewscanon.com> - 2011-04-07 21:24 -0400
                Re: calling own methods from constructor "Mike Schilling" <mscottschilling@hotmail.com> - 2011-04-09 22:06 -0700
            Re: calling own methods from constructor Tom Anderson <twic@urchin.earth.li> - 2011-04-07 23:10 +0100
              Re: calling own methods from constructor Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-04-07 22:24 +0000
        Re: calling own methods from constructor Lew <noone@lewscanon.com> - 2011-04-07 07:19 -0400
          Re: calling own methods from constructor Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-04-07 12:24 +0000
    Re: calling own methods from constructor Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-04-06 20:46 -0400
    Re: calling own methods from constructor Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-04-07 08:36 +0000
      Re: calling own methods from constructor Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-04-07 07:16 -0300
        Re: calling own methods from constructor Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-04-07 11:26 +0000
      Re: calling own methods from constructor Paul Cager <paul.cager@googlemail.com> - 2011-04-07 03:20 -0700
        Re: calling own methods from constructor Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-04-07 11:36 +0000
  Re: calling own methods from constructor Owen Jacobson <angrybaldguy@gmail.com> - 2011-04-06 22:23 -0400
    Re: calling own methods from constructor Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-04-07 09:13 +0000
      Re: calling own methods from constructor Tobias Blass <tobiasblass@gmx.net> - 2011-04-07 10:58 +0000
        Re: calling own methods from constructor Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-04-07 12:19 +0000
          Re: calling own methods from constructor Alessio Stalla <alessiostalla@gmail.com> - 2011-04-07 10:40 -0700
            Re: calling own methods from constructor Tobias Blass <tobiasblass@gmx.net> - 2011-04-07 19:00 +0000
              Re: calling own methods from constructor Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-04-07 20:11 +0000
              Re: calling own methods from constructor Jim Janney <jjanney@shell.xmission.com> - 2011-04-07 14:36 -0600
              Re: calling own methods from constructor Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-04-07 20:59 -0400
    Re: calling own methods from constructor Jim Janney <jjanney@shell.xmission.com> - 2011-04-07 10:26 -0600
      Re: calling own methods from constructor Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-04-07 20:16 +0000
      Re: calling own methods from constructor Lew <lew@lewscanon.com> - 2011-04-07 14:05 -0700
        Re: calling own methods from constructor Jim Janney <jjanney@shell.xmission.com> - 2011-04-07 16:15 -0600
          Re: calling own methods from constructor Lew <noone@lewscanon.com> - 2011-04-07 21:28 -0400
          Re: calling own methods from constructor Owen Jacobson <angrybaldguy@gmail.com> - 2011-04-07 23:21 -0400
            Re: calling own methods from constructor Owen Jacobson <angrybaldguy@gmail.com> - 2011-04-07 23:39 -0400
            Re: calling own methods from constructor Owen Jacobson <angrybaldguy@gmail.com> - 2011-04-07 23:58 -0400
            Re: calling own methods from constructor Tom Anderson <twic@urchin.earth.li> - 2011-04-08 20:32 +0100
      Re: calling own methods from constructor Tom Anderson <twic@urchin.earth.li> - 2011-04-07 23:05 +0100
        Re: calling own methods from constructor Jim Janney <jjanney@shell.xmission.com> - 2011-04-07 17:38 -0600
  Re: calling own methods from constructor Roedy Green <see_website@mindprod.com.invalid> - 2011-04-07 03:20 -0700
    Re: calling own methods from constructor Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-04-07 11:32 +0000
  Re: calling own methods from constructor Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2011-04-08 01:51 +0200
    Re: calling own methods from constructor Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2011-04-08 01:56 +0200
      Re: calling own methods from constructor Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-04-08 09:30 +0000
        Re: calling own methods from constructor Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2011-04-08 20:02 +0200

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