Hi Steve,
Yes, there's no release member function -- I'm going to add one. For now
you can do something like:
ptr = XObjectPtr();
If you're interested in seeing this restriction lifted, you can file a
enhancement request in Bugzilla.
Dave
"Oliver, Steve"
<Steve.Oliver@bestw To: <[EMAIL PROTECTED]>
estern.com> cc: (bcc: David N
Bertoni/Cambridge/IBM)
Subject: RE: XPathEvaluator question
01/23/2003 08:48 AM
Please respond to
xalan-dev
Dave,
Thanks for clearing that up for me. I suspected that what I should have
been doing was to release the XObjectPtr before my next call to evaluate().
I was looking for a release() function on the pointer object but couldn't
find one. I guess that 's what lead to my confusion.
Thanks again...
Steve
-----Original Message-----
From: David N Bertoni/Cambridge/IBM
[mailto:[EMAIL PROTECTED]]
Sent: Wednesday, January 22, 2003 6:51 PM
To: [EMAIL PROTECTED]
Subject: Re: XPathEvaluator question
Hi Steve,
I guess the documentation could be more explicit about this, but what it's
trying to say is you must copy any information out of the XObject instance
_before_ one of the following happens:
1. You make another call to any one of the member functions of the
XPathEvaluator instance.
2. The XPathEvaluator instance goes out of scope.
So you are correct in your guesses, and you must either plan your code so
any result is no longer in scope, or you release the XObject instance by
assigning a "null" XObjectPtr instance:
theResult1 = XObjectPtr();
This protocol may seem strange, but it was done that way to make sure the
entire execution environment is reset for the next evaluation.
We could lift the first restriction, if you think it's that onerous. We
can't lift the second one...
Dave
"Oliver, Steve"
<Steve.Oliver@bestw To: "Xalan Dev"
<[EMAIL PROTECTED]>
estern.com> cc: (bcc: David N
Bertoni/Cambridge/IBM)
Subject: XPathEvaluator
question
01/22/2003 05:22 PM
Please respond to
xalan-dev
All,
I'm using Xalan-C++ to evaluate multiple xpath expressions on a single xml
file. The first expression evaluates fine but the next call to the evaluate
function causes my program to crash with the following message...
Assertion failed: m_referenceCount == 0, file
xalan-c-src1_4_0\xml-xalan\c\src\PlatformSupport\XalanReferenceCountedObject.cpp,
line 80
Here's a code fragment
expression = "//CityName";
const XObjectPtr
theResult1(theEvaluator.evaluate(theDOMSupport, theContextNode,
XalanDOMString(expression.data()).c_str(),
theDocument->getDocumentElement()));
...
expression = "//CityName/@PostalCode";
const XObjectPtr
theResult2(theEvaluator.evaluate(theDOMSupport, theContextNode,
XalanDOMString(expression.data()).c_str(),
theDocument->getDocumentElement()));
Apparently some object is being destroyed while its refCount is not zero.
I'm assuming that it's the XObjectPtr. The documentation is somewhat
confusing regarding how the return object from the
XPathEvaluator::evaluate() is handled.
"The result is returned as a generalized object. The object will be
destroyed when the returned when the user's copy of the returned XObjectPtr
<http://xml.apache.org/xalan-c/apidocs/class_xobjectptr.html> goes out of
scope, or when the XPathEvaluator goes out of scope or another expression
is evaluated."
Does this mean that theResult's destructor is called when I make the second
call to evaluate()?
"The user's XObjectPtr <
http://xml.apache.org/xalan-c/apidocs/class_xobjectptr.html> copy _must_
no longer be in scope when the XPathEvaluator instance goes out of scope,
or another expression is evaluated."
Does this mean that it's an error for theResult to remain in scope when I
make the second call to evaluate()?
Can someone explain in a little more detail how this returned object is
handled between successive calls to the evaluate function.
Do I have to create a new pointer object for the return value of each
evaluate()?
Why does this not work?
Thanks for the help...
Steve
