Groups > comp.lang.java.programmer > #2930

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> <inip6r$l2n$1@news.albasani.net> <slrnipqubm.phi.avl@gamma.logic.tuwien.ac.at> <41ac2ca5-83e8-4b80-92af-9704b373ec37@q36g2000yqn.googlegroups.com>
Message-ID	<slrniprbm5.phi.avl@gamma.logic.tuwien.ac.at> (permalink)
Date	2011-04-07 12:32 +0000

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Robert Klemme <shortcutter@googlemail.com> wrote:
> On 7 Apr., 10:44, Andreas Leitgeb <a...@gamma.logic.tuwien.ac.at>
> wrote:
>> Lew <no...@lewscanon.com> wrote:
>> > 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?
>>
>> > import org.apache.log4j.Logger;
>> > import static org.apache.log4j.getLogger;
>> > public class Foo
>> > {
>> >     private final Logger logger = getLogger( getClass() );
>> >   // ...
>> > }
>>
>> I thought, I made it clear, that calling static methods was not relevant
>> to my question.  So, kind of thanks for pointing out that I should have
>> written non-static in the very line of the question, rather than consider
>> that clear from the other (snipped by you) paragraphs of my post...
>
> Well, that is clear, but: getClass() isn't a static method.

Because getClass() is final, it didn't occur to me, that he
would have put up *that* as an example... 

> As for me, I can't remember having shot myself in the foot with this
> feature of Java (i.e. allowing to invoke virtual methods in
> constructor).  I reckon, language designers figured that allowing it
> is more worthwhile than preventing it.  As Thomas pointed out you
> would have to provide constructor arguments so subclasses can pass on
> data they have created.  This is tiresome and may even end up being
> inefficient namely in the case where the superclass constructor needs
> to decide which methods to call (or whether methods to call).  You
> would end up creating objects which then need to be discarded if the
> super class constructor decides that he does not need them =>
> inefficient code.

The example of that Library class-hierarchy looked a bit 
contrived to me.

> Btw, the check would be expensive for the compiler and I am also not
> sure how that byte code might look like because you need to extend the
> restrictions to all methods. [...]

It would be already an improvement, if direct calls to such
methods from the constructor were forbidden.

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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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