Finally after 3 weeks I have some spare time that I can assignate for JXTG.
Excelent!
Daniel Fagerstrom wrote:
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I like the getNode method even less and would like to get rid of it. I introduced it as JXPath both has a getNode method that returns the raw object pointed to and a getValue that does some extra work on it, (like the irritating xsl:value-of stuff on DOM). Now Expression.evaluate basically does JXPath getValue and Expression.getNode does JXPath getNode.
Could you describe the difference in more detail?
I don't know that much about it, I hoped that someone more knowledgeable about JXPath at the list would explain it. I also wonder how JXPath is used in the rest of Cocoon is the behaviour of getValue needed somewhere or would getNode work everywhere?
The main difference that I know about is that for DOM, getValue behave like xsl:value-of i.e. it returns the concatenated text nodes of the DOM as a string rather than the whole DOM tree. getNode is like xsl:copy-of for a DOM and returns the DOM object.
getNode always returns the actual object that the xpath points to while does some kind of transformation of the object for some object types. I didn't find any precise description of the difference in the documentation so we probably have to read the source to find out.
For JXTG, getNode is used for the value of jx:eval/@select, jx:out/@value, x:set/@value and for expressions in element content, everywhere else getValue or getIterator is used.
As there is no difference between getValue and getNode for Jexl in JXTG one would assume that getNode could be use everywhere for JXPath, but maybe there is a difference for DOM and people don't use Jexl for DOM. Maybe getNode returns CharacterNodes instead of strings for DOM. If that is the case I would anyway prefer leting expressions always returning the actual object pointed to and let the (hopefully) forthcomming converter component take care of converting objects to strings.
I would prefer to get rid of the Expression.getNode method and have Let Expression.evaluate basically call JXPath getNode. But I don't know enough about the consequances for e.g. JXTG, any opinions?
I see only one place now that could be problematic: <jx:set name="var" value="something"/> vs.
<jx:set name="var">something</jx:set>
Both are allowed and both should be treated differently.
They should, but I don't see how that is related to getNode/getValue? jx:set/@value uses getNode and jx:set/* executes the body and put the result in a DOM.
Questions =========
* Is the design reasonable? * Does it work for other ELs?
There is only one more EL used in cocoon: XReporter EL. Should we take it into account?
Yes we should. I don't know that much about XReporter EL, any volounters for implementing it?
/Daniel
