I managed to intercept the setting of the instance method with the
following:
myClassTemplate->PrototypeTemplate()->SetHandler(
NamedPropertyHandlerConfiguration(nullptr, [](Local<Name> property, Local<
Value> value, const PropertyCallbackInfo<Value>& info) {
printf("This will be called when setting the instance method on the
prototype");
}));
So the question remains only for the static method interception.
On Monday, March 2, 2020 at 11:10:26 AM UTC+2, Darin Dimitrov wrote:
>
> I am embedding V8 in my application and registered a custom class
> (MyClass). I am looking for a way to intercept the setting of methods on
> this class.
>
> Here's my code:
>
>
> auto platform = platform::NewDefaultPlatform();
> V8::InitializePlatform(platform.get());
> V8::Initialize();
> std::string flags = "--expose_gc --jitless";
> V8::SetFlagsFromString(flags.c_str(), flags.size());
> Isolate::CreateParams create_params;
> create_params.array_buffer_allocator = ArrayBuffer::Allocator::
> NewDefaultAllocator();
>
> Isolate* isolate = Isolate::New(create_params);
> {
> Isolate::Scope isolate_scope(isolate);
> HandleScope handle_scope(isolate);
>
> Local<FunctionTemplate> myClassTemplate = FunctionTemplate::New(
> isolate);
> Local<FunctionTemplate> myInstanceMethodTemplate = FunctionTemplate::
> New(isolate);
> myClassTemplate->InstanceTemplate()->Set(v8::String::NewFromUtf8(
> isolate, "myInstanceMethod", v8::NewStringType::kNormal).ToLocalChecked(),
> myInstanceMethodTemplate);
>
> Local<ObjectTemplate> globalTemplate = ObjectTemplate::New(isolate);
> globalTemplate->Set(v8::String::NewFromUtf8(isolate, "MyClass", v8::
> NewStringType::kNormal).ToLocalChecked(), myClassTemplate);
>
> Local<v8::Context> context = v8::Context::New(isolate, nullptr,
> globalTemplate);
> Context::Scope context_scope(context);
> {
> Local<v8::Function> myClassCtor = myClassTemplate->GetFunction(
> context).ToLocalChecked();
> Local<v8::Function> myStaticMethod = v8::Function::New(context,
> nullptr).ToLocalChecked();
> assert(myClassCtor->Set(context, v8::String::NewFromUtf8(isolate,
> "myStaticMethod", v8::NewStringType::kNormal).ToLocalChecked(),
> myStaticMethod).FromMaybe(false));
>
> std::string src = R"(
> // I want to intercept setting this static method and raise
> some C++ callback when this code is executed
> MyClass.myStaticMethod = () => { };
>
> // I want to intercept setting this instance method and raise
> some C++ callback when this code is executed
> MyClass.prototype.myInstanceMethod = () => { };
> )";
>
> Local<v8::String> source = v8::String::NewFromUtf8(isolate, src.
> c_str(), v8::NewStringType::kNormal).ToLocalChecked();
> Local<Script> script = Script::Compile(context, source).
> ToLocalChecked();
> Local<Value> result = script->Run(context).ToLocalChecked();
> assert(!result.IsEmpty());
> }
>
> }
>
> isolate->Dispose();
> V8::Dispose();
> V8::ShutdownPlatform();
> delete create_params.array_buffer_allocator;
>
>
>
> In this code I need a C++ callback to be raised when the script is trying
> to replace some existing static or instance method on my custom class.
>
> Is there some API in V8 that I can use to achieve that?
>
> I have tried registering a NamedPropertyHandlerConfiguration but my
> callback is never called:
>
> myClassTemplate->InstanceTemplate()->SetHandler(
> NamedPropertyHandlerConfiguration(nullptr, [](Local<Name> property, Local<
> Value> value, const PropertyCallbackInfo<Value>& info) {
> printf("ok");
> }));
>
>
> Basically I need a way to detect that some script is trying to replace the
> methods which I have registered manually.
>
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