# Plain and Meta-Pool Implementation with Custom Admin Controls

Source: [https://docs.curve.finance/developer/amm/stableswap-ng/implementations/custom1](https://docs.curve.finance/developer/amm/stableswap-ng/implementations/custom1)

This implementation enables \*\*arbitrary assignment of an `admin` and `admin_fee`\*\*for a specific pool. The `Factory.admin()` is, and will always remain, one of the pool’s owners—ensuring full control via the DAO.

Contract Implementations

The source code for the implementation can be found on GitHub in the [admin-implementation branch](https://github.com/curvefi/stableswap-ng/tree/admin-implementation). This implementation is initially used by CrossCurve on Sonic.

The implementations were added to the StableSwapFactory on Sonic via [Vote ID #1010](https://curve.fi/dao/ethereum/proposals/1010-OWNERSHIP/) and are deployed at `index = 710420`.

```py
>>> Factory.metapool_implementations(710420)
'0x8663426e8713922D81e44d73295759e74Afc230F'

>>> Factory.pool_implementations(710420)
'0xA7c2DD4356168153792EF05D27922064b3c71A26'
```

The implementation introduces the ability to designate an additional admin with the following permissions:

-   The admin has the authority to set the contract’s admin fee, which can range from 0% to 100%. Previously, this fee was hardcoded at 50%.
-   Once an `admin` is set, their address replaces the `fee_receiver` and starts receiving all pool admin fees. If no admin is set, the `fee_receiver` remains the default recipient.

At contract initialization, the admin is set to `ZERO_ADDRESS`. This means assigning a new admin requires a DAO vote via the `set_admin` function. The `admin_fee` defaults to 50% but can be updated later.

* * *

<a id="admin"></a>

### `admin`

`CurveStableSwap.admin() -> address: view`

Getter for the admin of the contract. At contract initialization, the address of the admin is always set to `ZERO_ADDRESS`.

Returns: admin of the contract (`address`).

**<>Source code▼**

```vyper
@external
def __init__(
    ...
):

    ...
    self.admin = empty(address)
    ...

admin: public(address)
```

**▶Example▼**

This example returns the current admin of the contract.

```shell
>>> CurveStableSwap.admin()
'0x0000000000000000000000000000000000000000'
```

<a id="set_admin"></a>

### `set_admin`

`CurveStableSwap.set_admin(_new_admin: address)`

Guarded Method

This function is only callable by the `admin` of the `Factory`.

Function to set the admin of the contract. Setting the admin will revert if its not called by the admin of the `Factory`.

Emits: `SetAdmin` event.

| Input | Type | Description |
| --- | --- | --- |
| `_new_admin` | `address` | New admin address. |

**<>Source code▼**

```vyper
interface Factory:
    def fee_receiver() -> address: view

event SetAdmin:
    admin: address

admin: public(address)

@external
def set_admin(_new_admin: address):
    assert msg.sender == factory.admin()  # dev: only owner

    self.admin = _new_admin
    log SetAdmin(_new_admin)

@view
@internal
def _check_admins():
    assert msg.sender == factory.admin() or msg.sender == self.admin  # dev: only admin
```

**▶Example▼**

This example sets the admin of the contract.

```shell
>>> CurveStableSwap.admin()
'0x0000000000000000000000000000000000000000'

>>> CurveStableSwap.set_admin('0x7a16ff8270133f063aab6c9977183d9e72835428')

>>> CurveStableSwap.admin()
'0x7a16ff8270133f063aab6c9977183d9e72835428'
```

* * *

<a id="admin_fee"></a>

### `admin_fee`

`CurveStableSwap.admin_fee() -> uint256: view`

Getter for the admin fee of the pool. At contract initialization, the admin fee is set to 50%.

Returns: admin fee (`uint256`).

**<>Source code▼**

```vyper
@external
def __init__(
    ...
):

    ...
    self.admin_fee = 5000000000
    ...

admin_fee: public(uint256)
```

**▶Example▼**

This example returns the current admin fee of the contract.

```shell
>>> CurveStableSwap.admin()
'0x0000000000000000000000000000000000000000'
```

<a id="set_new_admin_fee"></a>

### `set_new_admin_fee`

`CurveStableSwap.set_new_admin_fee(_new_admin_fee: uint256):`

Guarded Method

This function is only callable by the `admin` of the `Pool` or the `Factory`.

Function to set the admin fee of the pool.

Emits: `SetAdmin` event.

| Input | Type | Description |
| --- | --- | --- |
| `_new_admin_fee` | `uint256` | New admin fee value. |

**<>Source code▼**

```vyper
interface Factory:
    def fee_receiver() -> address: view

event ApplyNewAdminFee:
    admin_fee: uint256

admin_fee: public(uint256)

FEE_DENOMINATOR: constant(uint256) = 10 **10

@external
def set_new_admin_fee(_new_admin_fee: uint256):
    self._check_admins()
    # FEE_DENOMINATOR = 1 = 100%
    assert _new_admin_fee <= FEE_DENOMINATOR  # dev: more than 100%

    self.admin_fee = _new_admin_fee
    log ApplyNewAdminFee(_new_admin_fee)

@view
@internal
def _check_admins():
    assert msg.sender == factory.admin() or msg.sender == self.admin  # dev: only admin
```

**▶Example▼**

This example sets the admin of the contract.

```shell
>>> StableSwapNG.admin_fee()
5000000000

>>> StableSwapNG.set_new_admin_fee(0)

>>> StableSwapNG.admin_fee()
0
```