自学教程：C++ HandleScope函数代码示例

void CJSKadID::FxToString(const v8::FunctionCallbackInfo<v8::Value> &args){	v8::HandleScope HandleScope(v8::Isolate::GetCurrent());	CJSKadID* jKadID = GetJSObject<CJSKadID>(args.Holder());	args.GetReturnValue().Set(v8::String::NewFromTwoByte(v8::Isolate::GetCurrent(), V8STR(jKadID->m_pKadID->m_Value.ToHex().c_str())));}

/** toString:* convert the buffer into a hex encoded string* * @return string*	Hex Encoded buffer content*/void CJSBuffer::FxToString(const v8::FunctionCallbackInfo<v8::Value> &args){	v8::HandleScope HandleScope(v8::Isolate::GetCurrent());	CBufferObj* pBuffer = GetCObject<CBufferObj>(args.Holder());	args.GetReturnValue().Set(v8::String::NewFromTwoByte(v8::Isolate::GetCurrent(), V8STR(ToHex(pBuffer->GetBuffer(), pBuffer->GetSize()).c_str())));}

PJsonVal TNodeJsStreamAggr::SaveJson(const int& Limit) const {	if (!SaveJsonFun.IsEmpty()) {		v8::Isolate* Isolate = v8::Isolate::GetCurrent();		v8::HandleScope HandleScope(Isolate);		v8::Local<v8::Function> Callback = v8::Local<v8::Function>::New(Isolate, SaveJsonFun);		v8::Local<v8::Object> GlobalContext = Isolate->GetCurrentContext()->Global();		const unsigned Argc = 1;		v8::Local<v8::Value> ArgV[Argc] = { v8::Number::New(Isolate, Limit) };		v8::TryCatch TryCatch;		v8::Local<v8::Value> ReturnVal = Callback->Call(GlobalContext, Argc, ArgV);		if (TryCatch.HasCaught()) {			TryCatch.ReThrow();				return TJsonVal::NewObj();		}		QmAssertR(ReturnVal->IsObject(), "Stream aggr JS callback: saveJson didn't return an object.");		PJsonVal Res = TNodeJsUtil::GetObjJson(ReturnVal->ToObject());		QmAssertR(Res->IsDef(), "Stream aggr JS callback: saveJson didn't return a valid JSON.");		return Res;	}	else {		return TJsonVal::NewObj();	}}

void TNodeJsFIn::Init(v8::Handle<v8::Object> exports) {	v8::Isolate* Isolate = v8::Isolate::GetCurrent();	v8::HandleScope HandleScope(Isolate);	// template for creating function from javascript using "new", uses _NewJs callback	v8::Local<v8::FunctionTemplate> tpl = v8::FunctionTemplate::New(Isolate, TNodeJsUtil::_NewJs<TNodeJsFIn>);	// child will have the same properties and methods, but a different callback: _NewCpp	v8::Local<v8::FunctionTemplate> child = v8::FunctionTemplate::New(Isolate, TNodeJsUtil::_NewCpp<TNodeJsFIn>);	child->Inherit(tpl);	child->SetClassName(v8::String::NewFromUtf8(Isolate, GetClassId().CStr()));	// ObjectWrap uses the first internal field to store the wrapped pointer	child->InstanceTemplate()->SetInternalFieldCount(1);		tpl->SetClassName(v8::String::NewFromUtf8(Isolate, GetClassId().CStr()));	// ObjectWrap uses the first internal field to store the wrapped pointer	tpl->InstanceTemplate()->SetInternalFieldCount(1);	// Add all prototype methods, getters and setters here	NODE_SET_PROTOTYPE_METHOD(tpl, "peekCh", _peekCh);	NODE_SET_PROTOTYPE_METHOD(tpl, "getCh", _getCh);    NODE_SET_PROTOTYPE_METHOD(tpl, "readLine", _readLine);    NODE_SET_PROTOTYPE_METHOD(tpl, "readJson", _readJson);	NODE_SET_PROTOTYPE_METHOD(tpl, "readAll", _readAll);	// Add properties	tpl->InstanceTemplate()->SetAccessor(v8::String::NewFromUtf8(Isolate, "eof"), _eof);	tpl->InstanceTemplate()->SetAccessor(v8::String::NewFromUtf8(Isolate, "length"), _length);	// This has to be last, otherwise the properties won't show up on the object in JavaScript		// Constructor is used when creating the object from C++	Constructor.Reset(Isolate, child->GetFunction());	// we need to export the class for calling using "new FIn(...)"	exports->Set(v8::String::NewFromUtf8(Isolate, GetClassId().CStr()),		tpl->GetFunction());}

void TNodeJsFIn::New(const v8::FunctionCallbackInfo<v8::Value>& Args) {    v8::Isolate* Isolate = v8::Isolate::GetCurrent();    v8::HandleScope HandleScope(Isolate);    if (Args.IsConstructCall()) {        EAssertR(Args.Length() == 1 && Args[0]->IsString(),            "Expected a file path.");        TStr FNm(*v8::String::Utf8Value(Args[0]->ToString()));        EAssertR(TFile::Exists(FNm), "File does not exist.");        TNodeJsFIn* JsFIn = new TNodeJsFIn(FNm);        v8::Local<v8::Object> Instance = Args.This();				v8::Handle<v8::String> key = v8::String::NewFromUtf8(Isolate, "class");		v8::Handle<v8::String> value = v8::String::NewFromUtf8(Isolate, ClassId.CStr());		Instance->SetHiddenValue(key, value);        JsFIn->Wrap(Instance);        Args.GetReturnValue().Set(Instance);    } else {        const int Argc = 1;        v8::Local<v8::Value> Argv[Argc] = { Args[0] };        v8::Local<v8::Function> cons = v8::Local<v8::Function>::New(Isolate, constructor);        v8::Local<v8::Object> Instance = cons->NewInstance(Argc, Argv);        Args.GetReturnValue().Set(Instance);    }}

TNodeJsRf24Radio* TNodeJsRf24Radio::NewFromArgs(const v8::FunctionCallbackInfo<v8::Value>& Args) {	v8::Isolate* Isolate = v8::Isolate::GetCurrent();	v8::HandleScope HandleScope(Isolate);	PJsonVal ParamJson = TNodeJsUtil::GetArgJson(Args, 0);	const int PinCE = ParamJson->GetObjInt("pinCE");	const int PinCSN = ParamJson->GetObjInt("pinCSN");	const uint16 MyId = (uint16) ParamJson->GetObjInt("id");	const PJsonVal SensorJsonV = ParamJson->GetObjKey("sensors");	const bool Verbose = ParamJson->GetObjBool("verbose", false);	const PNotify Notify = Verbose ? TNotify::StdNotify : TNotify::NullNotify;	Notify->OnNotify(TNotifyType::ntInfo, "Parsing configuration ...");	TStrIntH SensorNmIdH;	TStrIntH SensorIdNodeIdH;	for (int SensorN = 0; SensorN < SensorJsonV->GetArrVals(); SensorN++) {		const PJsonVal SensorJson = SensorJsonV->GetArrVal(SensorN);		const TStr& SensorId = SensorJson->GetObjStr("id");		SensorNmIdH.AddDat(SensorId, SensorJson->GetObjInt("internalId"));		SensorIdNodeIdH.AddDat(SensorId, SensorJson->GetObjInt("nodeId"));	}	Notify->OnNotify(TNotifyType::ntInfo, "Calling cpp constructor ...");	return new TNodeJsRf24Radio(MyId, PinCE, PinCSN, SensorNmIdH, SensorIdNodeIdH, Notify);}

TNodejsDHT11Sensor::TReadTask::TReadTask(const v8::FunctionCallbackInfo<v8::Value>& Args):		TNodeTask(Args),		JsSensor(nullptr) {	v8::Isolate* Isolate = v8::Isolate::GetCurrent();	v8::HandleScope HandleScope(Isolate);	JsSensor = ObjectWrap::Unwrap<TNodejsDHT11Sensor>(Args.Holder());}

void TNodeTask::AfterRunSync(const v8::FunctionCallbackInfo<v8::Value>& Args) {	v8::Isolate* Isolate = v8::Isolate::GetCurrent();	v8::HandleScope HandleScope(Isolate);	if (!Except.Empty()) { throw Except; }	Args.GetReturnValue().Set(WrapResult());}