On Sun, Apr 3, 2011 at 6:29 AM, developerdr <[email protected]> wrote:
> Dear Mads,
>
> thank you very much for your answer. Please find the simple example
> below (it took me some time to make it that small).
> The problem occurs even without the usage of additional threads.
> I think it's obviously that my code must have a logical mistake -
> because it's that simple.
> However, according to all the explanations provided in this mailing
> list and provided by the tutorials on the developer side I'm not able
> to find the problem...
>
> The example is written for windows and you should be able to test it
> using a simple console application.
> You will see that the crash occurs during the second context creation
> using the one and only static but persistent object template.
> As I understand the documentation of persistent objects: they are not
> influenced by the handle scope and thus the example should work fine.
> If you replace the usage of the static object template by two
> independent objects template the example does not crash...
>
> Thanks for you support,
> Jan
>
> #include <tchar.h>
> #include <cstdlib>
> #include <iostream>
> #include <cassert>
> #include <v8.h>
> #include <windows.h>
>
> /**
> * Simple singleton implementation.
> */
> class Singleton
> {
> public:
>
> /**
> * Returns the unique singleton object.
> */
> static Singleton& get()
> {
> static Singleton singleton;
> return singleton;
> }
>
> /**
> * Returns the unique object template.
> */
> v8::Persistent<v8::ObjectTemplate> objectTemplate()
> {
> if (uniqueObjectTemplate.IsEmpty())
> {
> uniqueObjectTemplate =
> v8::Persistent<v8::ObjectTemplate>(v8::ObjectTemplate::New());
Here's your problem. You're missing a "::New" and instead you're
casting a local to a persistent handle:
/**
* "Casts" a plain handle which is known to be a persistent handle
* to a persistent handle.
*/
template <class S> explicit inline Persistent(Handle<S> that)
: Handle<T>(*that) { }
Maybe V8 team could add an overload Persistent(Local) that triggers a
compile-time error, or at least a useful runtime error.
Matthias
>
> // normally here function templates would be
> added
>
> //uniqueObjectTemplate->Set(String::New("functionName"),
> createSpecificFunctionTemplate())
> }
>
> return uniqueObjectTemplate;
> }
>
> private:
>
> v8::Persistent<v8::ObjectTemplate> uniqueObjectTemplate;
> };
>
> int _tmain(int argc, _TCHAR* argv[])
> {
> {
> v8::HandleScope handleScope;
>
> {
> v8::Persistent<v8::Context> anyContext =
> v8::Context::New(NULL,
> Singleton::get().objectTemplate());
>
> // do something with this context
>
> anyContext.Dispose();
> }
> }
>
> {
> v8::HandleScope handleScope;
>
> {
> // ** CRASH ->
> v8::Persistent<v8::Context> anyContext =
> v8::Context::New(NULL,
> Singleton::get().objectTemplate());
> // <-- CRASH **
>
> // do something with this context
>
> anyContext.Dispose();
> }
> }
>
> std::cout << "Press a key to exit" << std::endl;
> getchar();
>
> return 0;
> }
>
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