[XML-SIG] SAX2: Attribute extensions

[uche.ogbuji@fourthought.com]

> This posting specifies two interfaces for information needed by the
> DOM (and possibly also others) and also for full XML 1.0 conformance.
> I'm not really sure whether we should actually use all of this, so
> opinions are welcome.
> 
> class AttributeList2:
> 
>   def isSpecified(self,attr):
>     """Returns true if the attribute was explicitly specified in the
>     document and false otherwise. attr can be the attribute name or
>     its index in the AttributeList."""

This is pretty much essential for full DOM support, and thus it would help us 
greatly for the SAX builder in 4DOM.

>   def getEntityRefList(self,attr):
>     """This returns the EntityRefList (see below) for an attribute,
>     which can be specified by name or index."""
> 
> The class below is inteded to be used for discovering entity reference
> boundaries inside attribute values. This is needed because the XML 1.0
> recommendation requires parsers to report unexpanded entity references, 
> also inside attribute values. Whether this is really
> something we want is another matter.

I'm not clear on what the alternative is.  For example,

<spam eggs="xx&monty;xx">

if the parser doesn't expand &monty;, do you suggest that it should instead 
just return the literal "xx&monty;xx" as the attribute value. leaving the 
application to spot the "&" and assume an entity reference appropriately?  
This seems rather a shift in burden to the app.  If this is not what you mean, 
then it would seem to make sense for the parser to report unexpanded entity 
refs.

> class EntityRefList:
> 
>   def getLength(self):
>     "Returns the number of entity references inside this attribute value."
> 
>   def getEntityName(self, ix):
>     "Returns the name of entity reference number ix (zero-based index)."
> 
>   def getEntityRefStart(self, ix):
>     """Returns the index of the first character inside the attribute
>     value that stems from entity reference number ix."""
> 
>   def getEntityRefEnd(self, ix):
>     "Returns the index of the last character in entity reference ix."
> 
> 
> One redeeming feature of this interface is that it lives entirely
> outside the attribute value, and so can be ignored entirely by those
> who are not interested.

-- 
Uche Ogbuji
FourThought LLC, IT Consultants
uche.ogbuji@fourthought.com	(970)481-0805
Software engineering, project management, Intranets and Extranets
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