# `Mojoler.Dsl.Box`
[🔗](https://github.com/thanos/mojoler/blob/v0.1.0/lib/mojoler/dsl/box.ex#L1)

A generated resource whose step function is `native/examples/box_user.mojo`.

`open/0` returns an opaque reference. The native object holds one signed
integer, starting at 0. That field is not visible to Elixir.

# `box`

```elixir
@type box() :: reference()
```

Opaque box handle. Inspects as a reference. The running total is native state.

# `bump`

```elixir
@spec bump(box(), integer()) :: integer()
```

Adds `delta` to the box and returns the new total.

`box` is a handle from `open/0`. `delta` is a signed integer. There is no
optional argument. The native step is `value + delta`.

## Raises

  * `ArgumentError` when `box` is not a box from this module, or `delta`
    is not an integer

## Examples

    iex> box = Mojoler.Dsl.Box.open()
    iex> Mojoler.Dsl.Box.bump(box, 20)
    20
    iex> Mojoler.Dsl.Box.bump(box, 22)
    42
    iex> Mojoler.Dsl.Box.bump(:nope, 1)
    ** (ArgumentError) argument error

# `load_nif`

```elixir
@spec load_nif() :: :ok | {:error, term()}
```

Loads `priv/native/libdsl_box.so`.

A second call returns `{:error, {:reload, charlist}}`.

## Examples

    iex> Mojoler.Dsl.Box.load_nif()
    {:error, {:reload, ~c"NIF library already loaded (reload disallowed since OTP 20)."}}

# `open`

```elixir
@spec open() :: box()
```

Opens a box whose total is 0.

## Returns

A `t:box/0`.

## Examples

    iex> box = Mojoler.Dsl.Box.open()
    iex> is_reference(box)
    true

---

*Consult [api-reference.md](api-reference.md) for complete listing*