[v8-users] Re: Could you provide actual up-to-date example of "Accessing Dynamic Variables", please?

[AleK Shmakov]

Thx Zac, my best bugged code is:
void GetPointX(Local<String> property,
               const PropertyCallbackInfo<Value>& info) {
    Local<Object> self = info.Holder();
    Local<External> wrap = Local<External>::Cast(self->GetInternalField(0));
    void* ptr = wrap->Value();
    int value = static_cast<Point*>(ptr)->x_;
    info.GetReturnValue().Set(value);
}

void SetPointX(Local<String> property, Local<Value> value,
               const PropertyCallbackInfo<void>& info) {
    Local<Object> self = info.Holder();
    Local<External> wrap = Local<External>::Cast(self->GetInternalField(0));
    void* ptr = wrap->Value();
    static_cast<Point*>(ptr)->x_ = value->Int32Value();
}

void v8_Point(const v8::FunctionCallbackInfo<v8::Value>& args) {
    printf("Is constructor call: %s\n", args.IsConstructCall()?"yes":"no");
    Point * p = new Point(12);
    printf("Internal field count: %d\n",args.This()->InternalFieldCount());
    args.This()->SetInternalField(0, External::New(args.GetIsolate(), p));
    args.GetReturnValue().Set(args.This());
}

ManagerV8::ManagerV8() {
    const char * temp_cc1 = "";
    V8::InitializeICUDefaultLocation(temp_cc1);
    V8::InitializeExternalStartupData(temp_cc1);
    platform = platform::CreateDefaultPlatform();
    V8::InitializePlatform(platform);
    V8::Initialize();
};

ManagerV8::~ManagerV8() {
    V8::Dispose();
    V8::ShutdownPlatform();
    delete platform;
}

std::string ManagerV8::v8_execute(const char* scriptSource, Point* 
shareVar) {            
    Isolate::CreateParams create_params;
    create_params.array_buffer_allocator = 
v8::ArrayBuffer::Allocator::NewDefaultAllocator();
    std::string temp_variable_result;

    Isolate* isolate = Isolate::New(create_params);
    {
        Isolate::Scope isolate_scope(isolate);
        HandleScope handle_scope(isolate);
        Local<ObjectTemplate> global_templ = ObjectTemplate::New(isolate);
        Local<FunctionTemplate> point_constructor = 
FunctionTemplate::New(isolate, v8_Point);
        point_constructor->InstanceTemplate()->SetInternalFieldCount(1);
        
point_constructor->InstanceTemplate()->SetAccessor(String::NewFromUtf8(isolate, 
"x"), GetPointX, SetPointX);

        Local<Context> context = Context::New(isolate, NULL, global_templ);
        Context::Scope context_scope(context);

        Local<String> source = String::NewFromUtf8(isolate, scriptSource, 
NewStringType::kNormal).ToLocalChecked();
        Local<Script> script = Script::Compile(context, 
source).ToLocalChecked();
        if(!script.IsEmpty()) {
            Local<Value> result = script->Run(context).ToLocalChecked();
            String::Utf8Value utf8(result);
            temp_variable_result = *utf8;
        }
    }

    isolate->Dispose();
    delete create_params.array_buffer_allocator;
    return temp_variable_result;
}
And the header:
class Point {
public:
    Point(int x) : x_(x) { }
    int x_;
};

class ManagerV8 {
    Platform* platform;

public:
    int x_;

    ManagerV8();
    ~ManagerV8();

    std::string v8_execute(const char* scriptSource, Point* shareVar);
};
As the result of JS code "*x+1;*" is:
<unknown>:12: Uncaught ReferenceError: x is not defined

#
# Fatal error in v8::ToLocalChecked
# Empty MaybeLocal.
#

Received signal 4 ILL_ILLOPN 000000cf345f

==== C stack trace ===============================

 [0x000000cf21ef]
 [0x7f06b9b088d0]
 [0x000000cf345f]
 [0x000002709e28]
[end of stack trace]

All this code based on stackoverflow and Embedder's guide.
Clear code of Embedder's guide don't work at all:

==== C stack trace ===============================

 [0x000000cf1dbf]
 [0x7fb45a6998d0]
 [0x0000004a2851]
 [0x00000073959e]
 [0x00000078534e]
 [0x000000784a2d]
 [0x00000072a8b7]
 [0x00000072b058]
 [0x0000007322fc]
 [0x2b4f6cd840dd]
[end of stack trace]





вторник, 25 апреля 2017 г., 6:41:29 UTC+7 пользователь Zac Hansen написал:
>
> it looks at least pretty close.   can you post some code and say what 
> specific problems you're having?   
>
> On Thursday, April 20, 2017 at 12:57:18 AM UTC-7, AleK Shmakov wrote:
>>
>> "Embedder's Guide" <https://github.com/v8/v8/wiki/Embedder%27s-Guide> 
>> unfotunatelly is not valid. 
>>
>

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