Errata 6

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(New page: The chapter 6 discusses '''protected abstract''' methods and says that removing such method is source compatible (page 89). In fact that was true until Java 5 appeared. However wit...)
Current revision (06:48, 11 October 2010) (edit) (undo)
 
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The [[chapter 6]] discusses '''protected abstract''' methods and says that removing such method is source compatible (page 89). In fact that was true until [[Java]] 5 appeared. However with the newly introduced ''@Override'' annotation this is no longer true.
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==== [[Errata 6|Page 89]] ====
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The [[chapter 6]] discusses '''protected abstract''' methods and says that removing such method is source compatible. In fact that was true until [[Java]] 5 appeared. However the newly introduced ''@Override'' [[annotation]] changed everything.
<source lang="java" snippet="anagram.ui.Anagrams"/>
<source lang="java" snippet="anagram.ui.Anagrams"/>
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-- Rijk van Haaften, Oct 8, 2010
-- Rijk van Haaften, Oct 8, 2010
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==== [[Errata 6|Page 90]] ====
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In the example of defining inserting new super class into existing class hierarchy, the whole source code should have been shown. The newly created ''SimpleHelloClass'' should define no argument method. The original ''HelloClass'' shall extend it and keep definition of the more complicated ''sayHelloTo'' method with one string argument:
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<source lang="java" snippet="design.insert.superclass1"/>
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<source lang="java" snippet="design.insert.superclass2"/>
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[[User:Cordeo|Cordeo]] 21:47, 7 October 2010 (UTC)

Current revision

Page 89

The chapter 6 discusses protected abstract methods and says that removing such method is source compatible. In fact that was true until Java 5 appeared. However the newly introduced @Override annotation changed everything. 

does not exists: anagram.ui.Anagrams

If you create a new version of public abstract class Anagrams dropping either getWordLibrary or getScrambler (or both), the @Override annotation in AnagramsWithConstructor will cause the compiler to complain: 

does not exists: anagram.ui.init

Source compatibility is gone. As an API designer of public class Anagrams you don't know whether your users (writing class AnagramsWithConstructor) will use @Override. As a result don't even try to remove protected abstract methods from an API. It was never good idea anyway and since Java 5 it is not backward compatible.

-- Rijk van Haaften, Oct 8, 2010

Page 90

In the example of defining inserting new super class into existing class hierarchy, the whole source code should have been shown. The newly created SimpleHelloClass should define no argument method. The original HelloClass shall extend it and keep definition of the more complicated sayHelloTo method with one string argument: 

does not exists: design.insert.superclass1
does not exists: design.insert.superclass2

Cordeo 21:47, 7 October 2010 (UTC)

Retrieved from "http://wiki.apidesign.org/wiki/Errata_6"
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