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Release 03.09.2024: migration guide

The latest release of =nil; introduces several changes to multi-token support and the minting mechanism.

Summary of key changes​

  • The Minter contract no longer exists and cannot be called from other smart contracts
  • The Nil.sol extension library now exposes the awaitCall() function that allows for making an async call to a smart contract and then awaiting the result
  • The JSON-RPC API now includes the eth_estimateFee method which can be used for gas estimations. Client tools (Nil.js and the =nil; CLI) will support this feature at a later date

Migration of smart contracts​

  • Mint tokens directly from smart accounts

All 'out of the box' smart accounts provided by =nil; can now mint tokens without having to refer to the Minter contract. As a result, the Minter contract has been discontinued. Any calls or transactions sent to this contract should be removed.

A more detailed overview of how to create tokens via smart accounts is provided in this tutorial.

  • Use NilTokenBase to create custom tokens

Instead of using the now non-existant Minter contract, create new custom tokens by deriving contracts from NilTokenBase:

import "path/to/NilTokenBase.sol";

contract Example is NilTokenBase {}

NilTokenBase base is a template contract that has all the necessary methods for mimicking the behavior of tokens including minting, token creation, and attaining the total token supply.

info

Derived contracts can override virtual functions inside NilTokenBase to change the default minting, transferring, or token creation behaviors.

  • Adjust the logic of smart contracts to account for awaitCall()

The awaitCall() function makes it possible to perform async calls between smart contracts while retrieving the returned value.

If necessary, change the logic of existing smart contracts to use awaitCall().

Migration of =nil; CLI​

No specific changes have to be made to existing =nil; CLI commands.

Note that the nil smart-account call-readonly command has been added. It allows for performing 'dry runs' of calling contracts via smart account. Provide the --with-details flag to see exactly how much fee credit could be spent on performing the operation tested during the 'dry run'.

Migration of Nil.js scripts​

  • Remove any transactions sent to the Minter contract

With the latest release, Nil.js changes the logic for creating and minting tokens.

To set the token name:

{
    const hashTransaction = await smartAccount.setTokenName("MY_TOKEN");
    await waitTillCompleted(client, hashTransaction);
}

To mint the token and withdraw it to its owner:

{
    const hashTransaction = await smartAccount.mintToken(100_000_000n);
    await waitTillCompleted(client, hashTransaction);
}

To transfer the token to another contract:

await smartAccount.sendTransaction({
    ...
    tokens: [
        {
            id: smartAccountAddress,
            amount: AMOUNT
        }
    ]
    ...
});

  • Adjust function signatures

  • The PublicClient.call() function no longer expects a from argument in its CallArgs and accepts feeCredit:

await client.call({
        to: address,
        feeCredit: 500000n,
        abi,
        functionName: "FUNC_NAME",
    }, "latest")
  • The waitTillCompleted() function accepts additional options allowing for waiting until the transaction with the given hash is included in a block in the main shard:
await waitTillCompleted(CLIENT, SHARD_ID, HASH, {
    waitTilMainShard: true,
    interval: INTERVAL
}
);

Migration of Hardhat scripts​

No specific changes have to be made to existing Hardhat scripts.