Libraries updates for extensions methods

["Zdeněk Troníček"]

Concerning the Iterator, I was always curious why there is not any class
ImmutableIterator with method remove() throwing UOE.

I found 89 implementations of Iterator in JDK 7.
35 of them implements remove() as { throw new UOE(); }.
29 out of these 35 implement directly Iterator, 6 implement ListIterator.
34 out of 35 could use ImmutableIterator or ImmutableListIterator because
they are either anonymous subclasses or classes that do not have any
explicit superclass.
Only once (CorbaContactInfoListIteratorImpl) this is not possible.

Wouldn't be the class ImmutableIterator more stylish?
(The numbers are without any warranty. I have not done any double check.)

Z.
-- 
Zdenek Tronicek
FIT CTU in Prague


Brian Goetz napsal(a):
> We're planning to introduce default methods to selected existing JDK
> classes on a resources-available basis.  An update of "all relevant JDK
> libraries", however, would be a massive effort, and is not currently
> resourced by Oracle.  (But OpenJDK is an open-source project, so others
> like yourself might be inclined towards such work.)
>
> I'm not an expert on DOM, but some of the examples you provide -- for
> example, default implementations throwing exceptions for "optional"
> methods -- seem like typical intended use cases for default methods.
> (For example, we'll add a default to Iterator.remove that throws UOE.)
>
> On 8/13/2012 10:16 AM, Daniel Latrémolière wrote:
>> Are you planning to update all relevant JDK libraries with extensions
>> methods, even parts without parallelism but with large interfaces and
>> repetitive methods like org.w3c.dom.*?
>>
>> A same DOM node can support multiple interfaces like some interfaces of
>> DOM Core, DOM Traversal and Range, DOM Load and Store, etc. Many of the
>> interfaces have repetitive methods.
>> It would also allow the big table at the beginning of Node javadoc to be
>> written in sub-interface extensions methods and not in implementation
>> classes.
>> It would not be a big change in Java world, but could be seen as cleaner
>> code (in my opinion), which is always better, even only when debugging.
>>
>> Thanks,
>> Daniel.
>>
>> |public interface Node {
>>       // NodeType
>>       public static final short ELEMENT_NODE = 1;
>>       public static final short ATTRIBUTE_NODE = 2;
>>       public static final short TEXT_NODE = 3;
>>       public static final short CDATA_SECTION_NODE = 4;
>>       public static final short ENTITY_REFERENCE_NODE = 5;
>>       public static final short ENTITY_NODE = 6;
>>       public static final short PROCESSING_INSTRUCTION_NODE = 7;
>>       public static final short COMMENT_NODE = 8;
>>       public static final short DOCUMENT_NODE = 9;
>>       public static final short DOCUMENT_TYPE_NODE = 10;
>>       public static final short DOCUMENT_FRAGMENT_NODE = 11;
>>       public static final short NOTATION_NODE = 12;
>>       public String getNodeName();
>>       public String getNodeValue() throws DOMException;
>>       public void setNodeValue(String nodeValue) throws DOMException;
>>       public short getNodeType();
>>       public Node getParentNode();
>>       public NodeList getChildNodes();
>>       public Node getFirstChild();
>>       public Node getLastChild();
>>       public Node getPreviousSibling();
>>       public Node getNextSibling();
>>       public NamedNodeMap getAttributes();
>>       public Document getOwnerDocument();
>>       public Node insertBefore(Node newChild, Node refChild) throws
>> DOMException;
>>       public Node replaceChild(Node newChild, Node oldChild) throws
>> DOMException;
>>       public Node removeChild(Node oldChild) throws DOMException;
>>       public Node appendChild(Node newChild) throws DOMException;
>>       public boolean hasChildNodes();
>>       public Node cloneNode(boolean deep);
>>       public void normalize();
>>       public boolean isSupported(String feature, String version);
>>       public String getNamespaceURI();
>>       public String getPrefix();
>>       public void setPrefix(String prefix) throws DOMException;
>>       public String getLocalName();
>>       public boolean hasAttributes();
>> }|
>>
>> A subinterface, like an attribute, add new abstract methods:
>> |public interface Attr extends Node {
>>       public String getName();
>>       public boolean getSpecified();
>>       public String getValue();
>>       public void setValue(String value) throws DOMException;
>>       public Element getOwnerElement();
>> }
>> |
>> But Attribute define default behaviour for many superinterface methods
>> and this behaviour can be expressed with extension methods:
>> |public interface Attr extends Node {
>>       public String getName();
>>       public boolean getSpecified();
>>       public String getValue();
>>       public void setValue(String value) throws DOMException;
>>       public Element getOwnerElement();
>>       public default String getNodeName() {
>>           return getName();
>>       }
>>       public ||default ||String getNodeValue() throws DOMException {
>> ||return ||getValue();
>>       }
>>       public ||default ||void setNodeValue(String nodeValue) throws
>> DOMException {
>>           setValue(nodeValue);
>>       }
>>       public ||default ||short getNodeType() {
>>           return Node.ATTRIBUTE_NODE;
>>       }
>>       public ||default ||Node getParentNode() {
>>           return getOwnerElement();
>>       }
>>       public ||default ||NodeList getChildNodes() {
>>           return EMPTY_NODE_LIST;
>>       }
>>       public ||default ||Node getFirstChild() {
>>           return null;
>>       }
>>       public ||default ||Node getLastChild() {
>>           return null;
>>       }
>>       public ||default ||NamedNodeMap getAttributes() {
>>           return null;
>>       }
>>       public ||default ||Node insertBefore(Node newChild, Node refChild)
>> throws DOMException {
>>           throw new DOMException();
>>       }
>>       public ||default ||Node replaceChild(Node newChild, Node oldChild)
>> throws DOMException {
>>           throw new DOMException();
>>       }
>>       public ||default ||Node removeChild(Node oldChild) throws
>> DOMException {
>>           throw new DOMException();
>>       }
>>       public ||default ||Node appendChild(Node newChild) throws
>> DOMException {
>>           throw new DOMException();
>>       }
>>       public ||default ||boolean hasChildNodes() {
>>           return false;
>>       }
>>       public ||default ||void normalize() {
>>       }
>>       public ||default ||boolean hasAttributes() {
>>           return false;
>>       }
>> }|
>>
>
>
>