Last modified by cds on 2025/01/30 12:03
<
From version < 23.1 >
edited by cds
on 2012/10/24 17:31
To version < 24.1 >
edited by cds
on 2012/10/24 17:48
>
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... ... @@ -409,7 +409,7 @@
409 409  We will now add a class that will be in charge of loading all extensions registered at our new extension point.
410 410  
411 411  1. (((
412 -Add a class {{code language="none"}}HeadControllers{{/code}} to the package {{code language="none"}}de.cau.cs.rtprak.login.simple.controller{{/code}}. Add the following code:
412 +Add a class {{code language="none"}}HeadControllers{{/code}} to the package {{code language="none"}}de.cau.cs.rtprak.login.simple.controller{{/code}}. Add the following code, replacing {{code language="none"}}login{{/code}} with your login name in {{code language="none"}}EXTENSION_POINT_ID{{/code}} as usual:
413 413  
414 414  {{code language="java"}}
415 415  /**
... ... @@ -419,7 +419,7 @@
419 419   */
420 420  public class HeadControllers {
421 421   /** Identifier of the extension point */
422 - public final static String EXTENSION_POINT_ID = "de.cau.cs.rtprak.groupx.simple.headControllers";
422 + public final static String EXTENSION_POINT_ID = "de.cau.cs.rtprak.login.simple.headControllers";
423 423   /** The singleton instance of the {@code HeadControllers} class */
424 424   public final static HeadControllers INSTANCE = new HeadControllers();
425 425   /** list of head controller ids with associated names. */
... ... @@ -552,32 +552,51 @@
552 552  1*. Set the current head position to 1.
553 553  1*. Refresh the table viewer with its {{code language="none"}}refresh(){{/code}} method.
554 554  
555 -
555 +== Adding a Test Head Controller ==
556 556  
557 -
557 +Before creating a proper head controller in another plug-in, we will add a test controller to check whether all this stuff works.
558 558  
559 -
559 +1. (((
560 +Add a new class {{code language="none"}}NullController{{/code}} to the {{code language="none"}}de.cau.cs.rtprak.login.simple.controllers{{/code}} package:
560 560  
561 -
562 +{{code language="java"}}
563 +/**
564 + * Head controller that does nothing, for testing.
565 + * @author msp
566 + */
567 +public class NullController implements IHeadController {
568 + /**
569 + * {@inheritDoc}
570 + */
571 + public HeadCommand nextCommand(final char character) {
572 + return new HeadCommand(Action.NULL, Direction.NONE, '_');
573 + }
574 +
575 + /**
576 + * {@inheritDoc}
577 + */
578 + public void reset() {
579 + }
580 +}
581 +{{/code}}
582 +)))
583 +1. Open the //Plugin Manifest Editor// and switch to the //Extensions// tab. Add your {{code language="none"}}de.cau.cs.rtprak.login.simple.headControllers{{/code}} extension point. Add a {{code language="none"}}controller{{/code}} element with ID {{code language="none"}}de.cau.cs.rtprak.login.simple.nullController{{/code}}, name {{code language="none"}}Null Controller{{/code}}, and class {{code language="none"}}de.cau.cs.rtprak.login.simple.controller.NullController{{/code}}.
584 +1. Start the application and observe how your program behaves if you change the action and direction in the {{code language="none"}}NullController{{/code}} class. You can actually change both while the application is running, but only if you have started it in the Debug mode. In that case, Eclipse will actually hot-swap your changes into the running application. Sorcery!
562 562  
563 -
586 +== Implementing Your Own Head Controller ==
564 564  
565 -
588 +We will now create a new plug-in with a new head controller:
566 566  
567 -
590 +1. Create a new plug-in {{code language="none"}}de.cau.cs.rtprak.login.simple.extension{{/code}}. In the //Plugin Manifest Editor//, add {{code language="none"}}de.cau.cs.rtprak.login.simple{{/code}} to the dependencies of the new plug-in.
591 +1. Create a new class that implements {{code language="none"}}IHeadController{{/code}}:\\
592 +1*. Assuming that the initial head position is 1, the controller shall copy the input text infinitely often. So if the tape initially contains the word {{code language="none"}}hello{{/code}}, the controller shall generate {{code language="none"}}hellohellohellohe...{{/code}} .
593 +1*. Your class needs some private fields to store the internal state of the controller, and you may need some special character as marker. Imagine how a Turing Machine would do this.
594 +1*. It is not allowed to store data that can grow infinitely, since a Turing Machine may only have a finite number of states. This means that you may store single characters or numbers, but you must not store Strings, StringBuffers, arrays, lists, or sets.
595 +1. Register the new controller class using an extension in the new plug-in.
596 +1. Test your controller.
568 568  
569 -
598 += Congratulations! =
570 570  
571 -
600 +Congratulations, you just made a big step towards understanding how Eclipse works. Plus, you've refreshed your knowledge on Turing Machines along the way. Eclipse is an industry standard technology, and having experience programming against it is a valuable skill for you.
572 572  
573 -
574 -
575 -
576 -
577 -
578 -
579 -
580 -
581 -
582 -
583 -
602 +If you have any comments and suggestions for improvement concerning this tutorial, please don't hesitate to tell us about them!
Confluence.Code.ConfluencePageClass[0]
Id
... ... @@ -1,1 +1,1 @@
1 -2982314
1 +2982316
URL
... ... @@ -1,1 +1,1 @@
1 -https://rtsys.informatik.uni-kiel.de/confluence//wiki/spaces/WS12EclPract/pages/2982314/The Plug-in Architecture of Eclipse
1 +https://rtsys.informatik.uni-kiel.de/confluence//wiki/spaces/WS12EclPract/pages/2982316/The Plug-in Architecture of Eclipse

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