doc: Added documentation for PropertyDescriptor

PR-URL: #309
Reviewed-By: Michael Dawson <[email protected]>

Author: Anisha Rohra

doc/property_descriptor.md

@@ -1,5 +1,141 @@
-# property descriptor
+# Property Descriptor
+
+An [Object](object.md) can be assigned properites via its [DefineProperty](object.md#defineproperty) and [DefineProperties](object.md#defineproperties) function, which take PropertyDescrptor(s) as their parameters. The PropertyDescriptor can contain either values or functions, which are then assigned to the Object. Note that a single instance of a PropertyDescriptor class can only contain either one value, or at most two functions. PropertyDescriptors can only be created through the class methods [Accessor](#accessor), [Function](#function), or [Value](#value), each of which return a new static instance of a PropertyDescriptor.
+
+## Example
+
+```cpp
+#include <napi.h>
+
+using namespace Napi;
+
+Value TestGetter(const CallbackInfo& info) {
+   return Boolean::New(info.Env(), testValue);
+}
+
+void TestSetter(const CallbackInfo& info) {
+   testValue = info[0].As<Boolean>();
+}
+
+Value TestFunction(const CallbackInfo& info) {
+   return Boolean::New(info.Env(), true);
+}
+
+Void Init(Env env) {
+   // Accessor
+   PropertyDescriptor pd1 = PropertyDescriptor::Accessor("pd1", TestGetter);
+   PropertyDescriptor pd2 = PropertyDescriptor::Accessor("pd2", TestGetter, TestSetter);
+
+   // Function
+   PropertyDescriptor pd3 = PropertyDescriptor::Function("function", TestFunction);
+
+   // Value
+   Boolean true_bool = Boolean::New(env, true);
+   PropertyDescriptor pd4 = PropertyDescriptor::Value("boolean value", TestFunction, napi_writable);
+
+  // Assign to an Object
+  Object obj = Object::New(env);
+  obj.DefineProperties({pd1, pd2, pd3, pd4});
+}
+```
+
+## Methods
+
+### Constructor
+
+```cpp
+Napi::PropertyDescriptor::PropertyDescriptor (napi_property_descriptor desc);
+```
+
+* `[in] desc`: A PropertyDescriptor that is needed in order to create another PropertyDescriptor.
+
+### Accessor
+
+```cpp
+static PropertyDescriptor Napi::PropertyDescriptor::Accessor (___ name,
+                Getter getter,
+                napi_property_attributes attributes = napi_default,
+                void *data = nullptr);
+```
+
+* `[in] name`: The name used for the getter function.
+* `[in] getter`: A getter function.
+* `[in] attributes`: Potential attributes for the getter function.
+* `[in] data`: A pointer to data of any type, default is a null pointer.
+
+Returns a PropertyDescriptor that contains a function.
+
+The name of the property can be any of the following types:
+- `const char*`
+- `const std::string &`
+- `napi_value value`
+- `Name`
+
+```cpp
+static PropertyDescriptor Napi::PropertyDescriptor::Accessor (___ name,
+                Getter getter,
+                Setter setter,
+                napi_property_attributes attributes = napi_default,
+                void *data = nullptr);
+```
+
+* `[in] name`: The name of the getter and setter function.
+* `[in] getter`: The getter function.
+* `[in] setter`: The setter function.
+* `[in] attributes`: Potential attributes for the getter function.
+* `[in] data`: A pointer to data of any type, default is a null pointer.
+
+Returns a PropertyDescriptor that contains a Getter and Setter function.
+
+The name of the property can be any of the following types:
+- `const char*`
+- `const std::string &`
+- `napi_value value`
+- `Name`
+
+### Function
+
+```cpp
+static PropertyDescriptor Napi::PropertyDescriptor::Function (___ name,
+                Callable cb,
+                napi_property_attributes attributes = napi_default,
+		            void *data = nullptr);
+```
+
+* `[in] name`: The name of the Callable function.
+* `[in] cb`: The function
+* `[in] attributes`: Potential attributes for the getter function.
+* `[in] data`: A pointer to data of any type, default is a null pointer.
+
+Returns a PropertyDescriptor that contains a callable Function.
+
+The name of the property can be any of the following types:
+- `const char*`
+- `const std::string &`
+- `napi_value value`
+- `Name`
+
+### Value
+
+```cpp
+static PropertyDescriptor Napi::PropertyDescriptor::Value (___ name,
+                napi_value value,
+                napi_property_attributes attributes = napi_default);
+```
+
+The name of the property can be any of the following types:
+- `const char*`
+- `const std::string &`
+- `napi_value value`
+- `Name`
+
+## Related Information
+
+### napi\_property\_attributes
+`napi_property_attributes` are flags used to indicate to JavaScript certain permissions that the property is meant to have. The following are the flag options:
+- napi\_default,
+- napi\_writable,
+- napi\_enumerable,
+- napi\_configurable
+For more information on the flags and on napi\_property\_attributes, please read the documentation [here](https://github.com/nodejs/node/blob/master/doc/api/n-api.md#napi_property_attributes).
 
-You are reading a draft of the next documentation and it's in continuous update so
-if you don't find what you need please refer to:
-[C++ wrapper classes for the ABI-stable C APIs for Node.js](https://nodejs.github.io/node-addon-api/)