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Re: A question about some long java code that has getters/setters

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On 7/25/2011 7:50 PM, markspace wrote:
> On 7/25/2011 1:27 PM, Patrick May wrote:
>> It encourages a style of programming where
>> objects have too much knowledge about each other.
>
>
> This is an interesting idea. However, I think it might be short sighted,
> or at least incomplete.
>
> For example, I've just been working on a project which involves sending
> commands over a network. There are up to four parameters for all
> commands, and it might be better style to perhaps only create some
> number of constructors which only allow valid combinations of these four
> parameters.
>[... uses "vanilla" constructor plus mutators ...]

     Another approach -- which may or may not make sense in your
situation, but might be worthy of consideration -- is to make Command
immutable, with one constructor that takes a single argument of the
mutable CommandBuilder class.

	public class Command {
	    private final int tweedeldum;
	    private final Control[] tweedledee;
	    ...
	    public Command(CommandBuilder builder) {
	        if (builder.isValid()) {
	            tweedledum = builder.tweedledum;
	            tweedledee = builder.tweedeldee.clone();
	            ...
	        } else {
	            throw new IllegalArgumentException(
	                builder.toString());
	        }
	    }
	}

	public class CommandBuilder {
	    private int tweedledee = 42;
	    private Control[] tweedledum = new Control[0];
	    ...
	    public CommandBuilder setTweedledee(int tweedledee) {
	        this.tweedledee = tweedledee;
	        return this;
	    }
	    public CommandBuilder setTweedledum(Control[] tweedledum) {
	        this.tweedledum = tweedledum;
	        return this;
	    }
	    ...
	}

	...

	Command makeItSo = new Command(
	    new CommandBuilder().setTweedledee(97));
	Command avastYeScurvySpalpeens = new Command(
	    new CommandBuilder().setTweedledum(getControls())
	        .setTweedledee(-86));

     True, the validation and exception-throwing still happen at
run-time -- but it happens at Command construction, instead of later
on when the Command is used and the source of the bad parameters may
be more of a mystery.

-- 
Eric Sosman
esosman@ieee-dot-org.invalid

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A question about some long java code that has getters/setters Chad <cdalten@gmail.com> - 2011-07-22 16:12 -0700
  Re: A question about some long java code that has getters/setters Arne Vajhøj <arne@vajhoej.dk> - 2011-07-22 19:28 -0400
  Re: A question about some long java code that has getters/setters Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-07-22 23:31 +0000
  Re: A question about some long java code that has getters/setters markspace <-@.> - 2011-07-22 16:51 -0700
  Re: A question about some long java code that has getters/setters lewbloch <lewbloch@gmail.com> - 2011-07-23 09:02 -0700
    Re: A question about some long java code that has getters/setters blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-23 17:41 +0000
      Re: A question about some long java code that has getters/setters lewbloch <lewbloch@gmail.com> - 2011-07-23 11:42 -0700
      Re: A question about some long java code that has getters/setters Arne Vajhøj <arne@vajhoej.dk> - 2011-07-23 17:59 -0400
        Re: A question about some long java code that has getters/setters Steve Sobol <sjsobol@JustThe.net> - 2011-07-23 23:39 -0700
          Re: A question about some long java code that has getters/setters blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-25 19:44 +0000
          Re: A question about some long java code that has getters/setters lewbloch <lewbloch@gmail.com> - 2011-07-26 09:03 -0700
    Re: A question about some long java code that has getters/setters Arne Vajhøj <arne@vajhoej.dk> - 2011-07-23 19:26 -0400
      Re: A question about some long java code that has getters/setters lewbloch <lewbloch@gmail.com> - 2011-07-26 09:00 -0700
    Re: A question about some long java code that has getters/setters Patrick May <patrick@softwarematters.org> - 2011-07-25 16:27 -0400
      Re: A question about some long java code that has getters/setters markspace <-@.> - 2011-07-25 15:14 -0700
      Re: A question about some long java code that has getters/setters lewbloch <lewbloch@gmail.com> - 2011-07-25 15:56 -0700
        Re: A question about some long java code that has getters/setters Patricia Shanahan <pats@acm.org> - 2011-07-25 17:00 -0700
          Re: A question about some long java code that has getters/setters Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-07-25 21:17 -0400
      Re: A question about some long java code that has getters/setters markspace <-@.> - 2011-07-25 16:50 -0700
        Re: A question about some long java code that has getters/setters Gene Wirchenko <genew@ocis.net> - 2011-07-25 18:30 -0700
          Re: A question about some long java code that has getters/setters Patricia Shanahan <pats@acm.org> - 2011-07-25 18:41 -0700
          Re: A question about some long java code that has getters/setters lewbloch <lewbloch@gmail.com> - 2011-07-26 09:05 -0700
          Re: A question about some long java code that has getters/setters Gene Wirchenko <genew@ocis.net> - 2011-07-26 10:48 -0700
            Re: A question about some long java code that has getters/setters Gene Wirchenko <genew@ocis.net> - 2011-07-26 11:56 -0700
              Re: A question about some long java code that has getters/setters Patricia Shanahan <pats@acm.org> - 2011-07-26 13:34 -0700
                Re: A question about some long java code that has getters/setters lewbloch <lewbloch@gmail.com> - 2011-07-26 14:21 -0700
            Re: A question about some long java code that has getters/setters lewbloch <lewbloch@gmail.com> - 2011-07-26 14:20 -0700
        Re: A question about some long java code that has getters/setters Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-07-25 21:35 -0400
        Re: A question about some long java code that has getters/setters Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-07-26 06:59 -0300
    Re: A question about some long java code that has getters/setters Jukka Lahtinen <jtfjdehf@hotmail.com.invalid> - 2011-07-26 12:19 +0300
      Re: A question about some long java code that has getters/setters lewbloch <lewbloch@gmail.com> - 2011-07-26 09:08 -0700
        Re: A question about some long java code that has getters/setters Jukka Lahtinen <jtfjdehf@hotmail.com.invalid> - 2011-07-27 15:56 +0300
          Re: A question about some long java code that has getters/setters lewbloch <lewbloch@gmail.com> - 2011-07-27 14:14 -0700

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