Class property and descriptor

Property descriptor for use with Napi::ObjectWrap::DefineClass(). This is different from the standalone Napi::PropertyDescriptor because it is specific to each Napi::ObjectWrap<T> subclass. This prevents using descriptors from a different class when defining a new class (preventing the callbacks from having incorrect this pointers).

Example

```cpp

include

class Example : public Napi::ObjectWrap { public: static Napi::Object Init(Napi::Env env, Napi::Object exports); Example(const Napi::CallbackInfo &info);

private: static Napi::FunctionReference constructor; double _value; Napi::Value GetValue(const Napi::CallbackInfo &info); Napi::Value SetValue(const Napi::CallbackInfo &info); };

Napi::Object Example::Init(Napi::Env env, Napi::Object exports) { Napi::Function func = DefineClass(env, "Example", { // Register a class instance accessor with getter and setter functions. InstanceAccessor("value", &Example::GetValue, &Example::SetValue), // We can also register a readonly accessor by passing nullptr as the setter. InstanceAccessor("readOnlyProp", &Example::GetValue, nullptr) });

constructor = Napi::Persistent(func);
constructor.SuppressDestruct();
exports.Set("Example", func);

return exports;

}

Example::Example(const Napi::CallbackInfo &info) : Napi::ObjectWrap(info) { Napi::Env env = info.Env(); // ... Napi::Number value = info[0].As(); this->_value = value.DoubleValue(); }

Napi::FunctionReference Example::constructor;

Napi::Value Example::GetValue(const Napi::CallbackInfo &info) { Napi::Env env = info.Env(); return Napi::Number::New(env, this->_value); }

Napi::Value Example::SetValue(const Napi::CallbackInfo &info, const Napi::Value &value) { Napi::Env env = info.Env(); // ... Napi::Number arg = value.As(); this->_value = arg.DoubleValue(); return this->GetValue(info); }

// Initialize native add-on Napi::Object Init (Napi::Env env, Napi::Object exports) { Example::Init(env, exports); return exports; }

// Register and initialize native add-on NODE_API_MODULE(NODE_GYP_MODULE_NAME, Init) ```

The above code can be used from JavaScript as follows:

```js 'use strict';

const { Example } = require('bindings')('addon');

const example = new Example(11); console.log(example.value); // It prints 11 example.value = 19; console.log(example.value); // It prints 19 example.readOnlyProp = 500; console.log(example.readOnlyProp); // Unchanged. It prints 19 ```

Methods

Constructor

Creates new instance of Napi::ClassPropertyDescriptor descriptor object.

cpp Napi::ClassPropertyDescriptor(napi_property_descriptor desc) : _desc(desc) {}

• [in] desc: The napi_property_descriptor

Returns new instance of Napi::ClassPropertyDescriptor that is used as property descriptor inside the Napi::ObjectWrap<T> class.

Operator

cpp operator napi_property_descriptor&() { return _desc; }

Returns the original N-API napi_property_descriptor wrapped inside the Napi::ClassPropertyDescriptor

cpp operator const napi_property_descriptor&() const { return _desc; }

Returns the original N-API napi_property_descriptor wrapped inside the Napi::ClassPropertyDescriptor