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Comments on DOM L3 Core

From: Arnold, Curt <Curt.Arnold@hyprotech.com>
Date: Fri, 21 Sep 2001 15:51:38 -0600
Message-ID: <70E215722F6AD511820A000103D141D40AA58F@thor.aeathtl.com>
To: "'www-dom@w3.org'" <www-dom@w3.org>


Section 1.1.10: Mixed DOM implementations

"In a heterogenous document, elements from different modules expect different services and API's from the same Document object, since there can be one owner and root of the document hierarchy."

I assume the services are primarily node creation and maybe the better approach is to separate the NodeFactory type methods (and adoptNode) into an interface distinct from Document and add a
nodeFactory attribute to Node.  So instead of node.ownerDocument.createElement(""), you could also do node.nodeFactory.createElement("").  In a homogeneous environment, they would be equivalent, but
in a heterogeneous environment, the type of node returned could be different.

Trying to add a generic node to a specialized DOM would probably need to raise a WRONG_DOCUMENT_ERR since node identity would be different if you tried to transparently adopt the node.

Trying to do a getInterface("org.w3.svg","1.0") would be problematic if a document embedded two distinct implementations of SVG for example.

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Interface DOMImplementation:

Using the NodeFactory idea, createDocumentType and createDocument could go into the NodeFactory interface and getInterface would be unnecessary since you could get the specialized NodeFactory by
either asking an existing SVG (for example) node for its NodeFactory or getting the right type of DOMImplementation from the DOMImplementationRegistry.

Otherwise, getInterface should have a version argument.

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Document.actualEncoding:

If the intent is to describe the encoding of the XML document parsed to create the DOM, then .initialEncoding might be a better name.  Unclear how this is related (and also distinct) from the encoding
attribute and how these would change with or affect loading and saving.

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Document.standalone:

What should happen if standalone is set to true, but the document actually uses entities defined in the external subset?  Should this be read-only and calculated?  If encoding deserves both an
actual/initial state and a current state, should there be a Document.initialStandalone attribute.

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Document.strictErrorChecking:

Don't like this as a global since one piece of code might turn strict error checking off while another unrelated fragment depends on strict error checking.  

What is the particular penalty trying to be avoided?  If it is checking if names for validity, maybe a way to get a lax NodeFactory might suffice.

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Document.adoptNode:

This would be a candidate to move to a NodeFactory interface.

"from its parent child list" should read "from the child list of its parent" or "from its parent's child list".  Same phrasing appears elsewhere.

"Specified attribute nodes are adopted, and the generated Attr Nodes."

Are discarded?  Are adopted?  Inquiring minds want to know.

NOT_SUPPORTED_ERR should also list entity and notation, should DOCUMENT be DOCUMENT_NODE?

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Document.setBaseURI

The interaction between this and XML Base is confusing, given the name, one might think that it should add an xml:base attribute to the document element.  If it did that, why is it not a method on the
Element interface.

I think Document.systemId might be a better name and more consistent with  Entity.systemId, Notation.systemId and DocumentType.systemId.

On load, Document.systemId would be the URI used to load the document and changing Document.systemId would be like changing Document.encoding, a suggestion to the next save operation (and would change
the results from any baseURI attribute accesses.

Interface Node:

Per previous discussions, maybe add a Node.nodeFactory attribute.

Tree Position:

Should also be able to determine if two nodes are siblings (following or preceding) or immediate parent or child.  I don't have access to the Xpath spec at the moment (office internet connection is
down), however something like:

const unsigned short TREE_POSITION_DIFFERENT_DOCUMENT = 0x0; 
const unsigned short TREE_POSITION_SAME_DOCUMENT = 0x1; 
const unsigned short TREE_POSITION_PRECEDING = 0x3; 
const unsigned short TREE_POSITION_FOLLOWING = 0x5; 
const unsigned short TREE_POSITION_SIBLING = 0x9; 
//  combination of same document, preceding/following and sibling const unsigned short TREE_POSITION_FOLLOWING_SIBLING = 0xD; 
const unsigned short TREE_POSITION_PRECEDING_SIBLING = 0xB; 
const unsigned short TREE_POSITION_SAME_NODE = 0x11; 
const unsigned short TREE_POSITION_ATTR_OF_SAME_ELEMENT = 0x21; 
const unsigned short TREE_POSITION_ANCESTOR = 0x43;
const unsigned short TREE_POSITION_DESCENDANT = 0x85;
const unsigned short TREE_POSITION_PARENT = 0x143;
const unsigned short TREE_POSITION_CHILD = 0x285;

Intentionally combined bits when one condition is a more specialized form of another condition, so, for example, so if you return TREE_POSITION_PARENT, then (pos & TREE_POSITION_ANCESTOR) ==
TREE_POSITION_ANCESTOR && (pos & TREE_POSITION_PRECEDING) == TREE_POSITION_PRECEDING.

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Node.compareTreePosition:

Comparing two nodes of unrelated documents could return a code (TREE_POSITION_DIFFERENT_DOCUMENT) instead of raising an exception.
Should a behavior be defined if other = null?

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Node.getInterface()

Not positive this is needed or maybe it just needs to be refined.  Maybe it needs an interface and version attribute?  Something like:

var svgelem = node.getInterface("org.w3.svg","1.0","SVGElement");

However, if you split out the NodeFactory from the Document, then this might just become an alternative cast operation.

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Node.isSameNode()

node.isSameNode(other) appears to be functionally identical to (node.compareTreePosition(other) == TREE_POSITION_EXACT_SAME) except that compareTreePosition() will throw an exception if the nodes are
in different documents.  The two methods should be aligned so either they both throw WRONG_DOCUMENT_ERR or neither does (would prefer neither).

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Node.isSupported:

Possibly clarify that feature is case-insensitive and version is not specified means null or "".

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Node.lookupNamespacePrefix

What is the return value if the URI matches the default namespace? I'd recommend "#default", but it should be explicitly stated.

Should the method throw an exception if the namespaceURI is not a valid URI?

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Node.lookupNamespaceURI

How do you determine the default namespace?  Again I'd suggest a prefix value of "#default".

Should the method throw an exception if the prefix is not an NCName (or #default)?

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Node.removeChild

NOT_SUPPORTED_ERR: if this node !IF! of type Document,...

Same typo appears elsewhere.

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Node.setUserData()

Can key be null, empty string? 

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Text.isWhitespaceInElementContent:

Wouldn't Text.isElementContentWhitespace be a better name since it is consistent with the XML Info Set name and JAXP?

Should it throw an exception if there is not DTD or Schema?

How about adding an additional Text.isWhitespace to determine if the text is just whitespace without making a value judgement on whether it is ignorable?

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Text.wholeText

Maybe adjacentText, whole text might imply that you would get "Hello World" from either text node in this fragment:

<Foo>Hello<?somepi?> World</Foo>

Also, it says "all text of Text nodes"..., but shouldn't it also give text of EntityReferences (and probably explicitly mention CDATASections).


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Text.replaceWholeText

Again maybe replaceAdjacentText.

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DOMError.severity

No informative severity.  Might be useful to put more space between the values to allow graduation of severity.

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DOMError.message 

Assumes that we have fixed the locale.  Maybe a getMessage(DOMString locale) instead.

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DOMError.errorURI

Had suggested to the SAX group that they publish URI's for parse errors so you don't have to try to recognize errors by trying to recognize the message strings.

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DOMErrorHandler.handleError

... Multiple calls to the !!!handleEvent!!! method.
Received on Friday, 21 September 2001 17:54:20 GMT

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