# External (template)
Class `Napi::External<T>` inherits from class [`Napi::Value`][].
The `Napi::External` template class implements the ability to create a `Napi::Value` object with arbitrary C++ data. It is the user's responsibility to manage the memory for the arbitrary C++ data.
`Napi::External` objects can be created with an optional Finalizer function and optional Hint value. The Finalizer function, if specified, is called when your `Napi::External` object is released by Node's garbage collector. It gives your code the opportunity to free any dynamically created data. If you specify a Hint value, it is passed to your Finalizer function.
## Methods
### New
```cpp
template <typename T>
static Napi::External Napi::External::New(napi_env env, T* data);
```
- `[in] env`: The `napi_env` environment in which to construct the `Napi::External` object.
- `[in] data`: The arbitrary C++ data to be held by the `Napi::External` object.
Returns the created `Napi::External<T>` object.
### New
```cpp
template <typename T>
static Napi::External Napi::External::New(napi_env env,
T* data,
Finalizer finalizeCallback);
```
- `[in] env`: The `napi_env` environment in which to construct the `Napi::External` object.
- `[in] data`: The arbitrary C++ data to be held by the `Napi::External` object.
- `[in] finalizeCallback`: A function called when the `Napi::External` object is released by the garbage collector accepting a T* and returning void.
Returns the created `Napi::External<T>` object.
### New
```cpp
template <typename T>
static Napi::External Napi::External::New(napi_env env,
T* data,
Finalizer finalizeCallback,
Hint* finalizeHint);
```
- `[in] env`: The `napi_env` environment in which to construct the `Napi::External` object.
- `[in] data`: The arbitrary C++ data to be held by the `Napi::External` object.
- `[in] finalizeCallback`: A function called when the `Napi::External` object is released by the garbage collector accepting T* and Hint* parameters and returning void.
- `[in] finalizeHint`: A hint value passed to the `finalizeCallback` function.
Returns the created `Napi::External<T>` object.
### Data
```cpp
T* Napi::External::Data() const;
```
Returns a pointer to the arbitrary C++ data held by the `Napi::External` object.
[`Napi::Value`]: ./value.md
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