Hello Dave and all, Prior to Dave posting the example below of how to initialize Xalan/Xerces before instantiating library objects as member data, I figured out a way of doing it that also works, described below. I'd like to know if anyone has any thoughts regarding using a static member function vs. as separate class as Dave describes below. I'm not so far along that I couldn't switch if my method isn't good for some reason. I'm aware of usability issues such as the static function requiring the user to explicitly get/delete as opposed to just instantiating the classes and letting them go out of scope. I'm more concerned with any pitfalls this may cause in using the libraries, threading issues, and the like. The get/delete methods do implement a counter and I'm intending to go back and pthread_mutex them for thread safety. But before I spend much more effort on this I'd like to know if I'm heading down a dangerous path.
Thank you everyone for all your help these past couple of days. -will -----Original Message----- From: Will Sappington [mailto:[EMAIL PROTECTED] Sent: Wednesday, February 14, 2007 6:10 PM To: xalan-c-users@xml.apache.org Subject: RE: Problem evaluating XPath expressions Dave, thank you very much for taking the time to do this. I followed up my post below with another one later last night about an idea I hit upon that is essentially what you are saying below. I'm using a static member function, getInstance() that initializes the X libraries only on the first call and then instantiates a Profile class with 'new' and returns a pointer to the instance. As with your method below, the X library initialization occurs before the parserLiaison constructs as member data and everyone is happy. It appears to be working fine. I'll read your suggestions below more thoroughly for things I could do to improve my implementation. Thanks again for all your help, -will -----Original Message----- From: David Bertoni [mailto:[EMAIL PROTECTED] Sent: Wednesday, February 14, 2007 4:28 PM To: xalan-c-users@xml.apache.org Subject: Re: Problem evaluating XPath expressions Will Sappington wrote: <snip> Dave Bertoni wrote: If you're going to do Xerces-C and Xalan-C initialization in the constructor of your class, you'll need to create a simple class that initializes Xerces-C and Xalan-C in the right order, and make that class a member of your class, ensuring that it appears before any other Xerces-C or Xalan-C class in the class definition. Here's an example, in pseudo-code: class XercesXalanInit { public: XercesXalanInit() { if (++s_initCount == 1) { PlatformUtils::Initialize(); XalanTransformer::initialize(); } } ~XercesXalanInit() { if (--s_initCount == 0) { XalanTransformer::terminate(); PlatformUtils::Terminate(); } } static unsigned long s_initCount; }; XercesXalanInit::s_initCount = 0; class myClass { public: myClass() : m_init(), m_liason() { } // all my public member functions here... private: XercesXalanInit m_init; XalanSourceTreeParserLiaison m_liason; }; Ultimately, it's much better if you initialize Xerces-C and Xalan-C _once_, when your application starts, and not when each instance is created. Also, you'll notice that I put some counting in the XercesXalanInit init class, because you should only call them each once. Finally, if your application will be multi-threaded, you will either need to initialize the libraries once, before any threads start, or make the counting in XercesXalanInit thread-safe. Dave
