> For the complete documentation index, see [llms.txt](https://docs.talus.network/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.talus.network/reference/move/nexus_primitives/object_state.md).

# nexus\_primitives::object\_state

* [Struct `Inner`](#struct-inner)
* [Struct `Witness`](#struct-witness)
* [Constants](#constants)
* [Function `add`](#function-add)
* [Function `inner`](#function-inner)
* [Function `inner_mut`](#function-inner_mut)
* [Function `has_witness`](#function-has_witness)
* [Function `assert_witness`](#function-assert_witness)
* [Function `replace_witness`](#function-replace_witness)
* [Function `take_inner`](#function-take_inner)
* [Function `add_inner`](#function-add_inner)
* [Function `destroy`](#function-destroy)
* [Function `assert_upgrade_cap`](#function-assert_upgrade_cap)

### Struct `Inner`

Positional key for an object's exact stored layout.

A shared key is required because each object module must expose the same observable storage position without sharing its stored value type.

```move
public struct Inner has copy, drop, store
```

<details>

<summary>Fields</summary>

</details>

#### Struct `Witness`

Positional key for the package an object accepts as write authority.

This is separate from \[[`Inner`](#nexus_primitives_object_state_Inner)] because execution can change without a storage layout change.

```move
public struct Witness has copy, drop, store
```

<details>

<summary>Fields</summary>

</details>

#### Constants

```move
#[error]
const EWrongWitness: vector<u8> = b"Object does not accept this package witness";
```

```move
#[error]
const EWrongUpgradeCap: vector<u8> = b"Upgrade capability does not target the witness package";
```

#### Function `add`

Attach one stored layout and one package witness to a stable object.

```move
public fun add<W: store, I: store>(id: &mut sui::object::UID, witness: W, inner: I)
```

#### Function `inner`

Borrow the exact stored layout without changing package authority.

```move
public fun inner<I: store>(id: &sui::object::UID): &I
```

#### Function `inner_mut`

Borrow the exact stored layout after verifying package authority.

```move
public fun inner_mut<W: store, I: store>(id: &mut sui::object::UID): &mut I
```

#### Function `has_witness`

Return whether the object accepts the exact witness type.

```move
public fun has_witness<W: store>(id: &sui::object::UID): bool
```

#### Function `assert_witness`

Require the object to accept the exact witness type.

```move
public fun assert_witness<W: store>(id: &sui::object::UID)
```

#### Function `replace_witness`

Replace an exact source witness with an exact target witness.

```move
public fun replace_witness<Old: drop, store, New: store>(id: &mut sui::object::UID, witness: New)
```

#### Function `take_inner`

Remove and return the exact stored layout during a declared transition.

```move
public fun take_inner<I: store>(id: &mut sui::object::UID): I
```

#### Function `add_inner`

Attach the target layout during a declared transition.

```move
public fun add_inner<I: store>(id: &mut sui::object::UID, inner: I)
```

#### Function `destroy`

Destroy a stable identity after removing its typed fields.

The inner value is returned because only its defining module knows how to destroy resources contained by that layout.

```move
public fun destroy<W: drop, store, I: store>(id: sui::object::UID): I
```

#### Function `assert_upgrade_cap`

Require an upgrade capability whose latest package introduced `W`.

```move
public fun assert_upgrade_cap<W>(cap: &sui::package::UpgradeCap)
```


---

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