On Tue, 27 Jul 2010, Greg Brown wrote:
Call me naive or maybe just a newb but I didn't know that the order in which
attributes appear on an element in bxml mattered. I mean, in XML
<element attr1="d24" attr2="hahth"/>
and
<element attr2="hahth" attr1="d24"/>
are the same when considering each document's infoset.
That may be true, but in the DOM order has relevance. Attributes are
stored as a list, not a map. Pivot's org.apache.pivot.xml.Element class
provides both keyed and indexed access to attributes.
Huh? What language/implementation of the DOM are you referencing? I'm
looking at Java's org.w3c.dom.Node, in which an element's attributes are
represented by a org.w3c.dom.NamedNodeMap. The documentation for the
latter explicitly states that NamedNodeMap does not imply an ordering.
Anyway, a list is a map. Or to put it another way, any collection can be
represented by a list simply by enumerating the elements of that
collection in some way. That does not imply that that collection has some
kind of innate or natural ordering.
Yet there are clearly cases where the order in which the attributes are
written is key. The one I ran into a moment ago is pretty simple. The
following works
<ListView listData="['One', 'Two', 'Three']" selectedIndex="0"/>
while the following does not
<ListView selectedIndex="0" listData="['One', 'Two', 'Three']"/>
The latter throws an IndexOutOfBoundsException. Thoughts?
The first one works because the list data is set before the selected
index. The second one fails because the list is empty when the selected
index is set. If ordering did not matter, we'd have no way to know which
attribute to set first.
Exactly. There is nothing in the StAX spec that states that Attributes
are indexed by the order in which they are written.
Michael
