On Jun 26, 2012, at 7:38 PM, C. M. Sperberg-McQueen wrote:
> I've encountered an unexpected behavior in 1.0RC. I first encountered
> it in one of my own forms, but the simplest way to recreate it may be:
>
> (1) Load the writers.xml example from the 1.0RC distribution, or from
>
> http://www.agencexml.com/xsltforms/writers.xml
>
> (2) Click Show Books and Hide Books a few times.
>
> (3) Click Profiler.
>
> This ought in normal operation to produce a profile showing the profiler
> information we have all come to love. What it produces instead, at the
> moment, is a Javascript error message saying
>
> XSLTForms Exception
> --------------------------
>
> Error dispatching event 'xforms-model-construct' :
>
> xforms-link-exception
I think I have now identified the source of this error.
Adding calls to Xsltforms_browser.debugConsole.write
at various locations makes clear that the error is arising in the
Xsltforms_globals.profiling_data() function, specifically in the loop
for (var expr in XsltForms_xpath.expressions) {
if (XsltForms_xpath.expressions.hasOwnProperty(expr)) {
exprtab[exprtab.length] = {expr: expr,
evaltime: XsltForms_xpath.expressions[expr].evaltime};
}
}
When I load writers.xml and click the Profiler button before having
unloaded any author's booklist, then this loop executes eight times,
for the expressions
. != 'true'
@firstname
@lastname
@selected
@selected != 'true'
@selected = 'true'
choose(@selected != 'true', 'Show', 'Hide')
writer
These are the XPath expressions occurring in writers.xml.
When I load the subform, by clicking Show Books, and then click Profiler,
the loop executes eleven times: eight times for the XPath expressions shown
above, and three more times for
@title
@year
book
These are the XPath expressions in books.xml, the subform.
When I then unload the subform by clicking Hide Books, and click Profiler
a third time, I get an error message in the Profiler window, and the debugging
trace in the main-form window shows the loop being entered nine times; it
looks a lot as if the error were being raised when the loop tries to evaluate
XsltForms_xpath.expressions['@title'].evaltime.
A little further examination suggests that after the subform is
unloaded, XsltForms_xpath.expressions['@title'] is null, so
the attempt to get its 'evaltime' property produces an error,
which causes the load of the profiler to fail.
Changing the conditional in lines 302-304 of xsltforms.js (in 1.0RC) to
if (XsltForms_xpath.expressions.hasOwnProperty(expr) &&
XsltForms_xpath.expressions[expr]) {
exprtab[exprtab.length] = {expr: expr, evaltime:
XsltForms_xpath.expressions[expr].evaltime};
}
seems to allow the Profiler to launch normally even after the subform is
unloaded.
Michael
--
****************************************************************
* C. M. Sperberg-McQueen, Black Mesa Technologies LLC
* http://www.blackmesatech.com
* http://cmsmcq.com/mib
* http://balisage.net
****************************************************************
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