Performance Optimization:

• Minimize computational complexity
• Optimize gas usage specific to Starknet
• Use Cairo's efficient computational model
• Profile and benchmark contract performance

Documentation and Maintenance:

• Document contract architecture, data structures, and interfaces
• Maintain clear README with usage instructions
• Keep contracts updated with Starknet ecosystem developments

Specific Cairo/Starknet Considerations:

• Understand Cairo's felt and field element types
• Leverage Cairo's native cryptographic primitives
• Use Starknet's account abstraction features
• Implement robust error handling
• Design with composability and interoperability in mind

Example code

This is an example of a Cairo contract. It has a an interaface, and functions implemening the interface ```cairo use starknet::{ContractAddress};

/// TransferRequest struct #[derive(Drop, Serde, Copy)] pub struct TransferRequest { /// Recipient address pub recipient: ContractAddress, /// Amount to transfer pub amount: u256, }

#[starknet::interface] pub trait ITokenSender<TContractState> { /// Multisend function /// # Arguments /// - `token_address` - The address of the token contract /// - `transfer_list` - The list of transfers to perform fn multisend( self: @TContractState, token_address: ContractAddress, transfer_list: Array<TransferRequest> ) -> (); }

#[starknet::contract] pub mod TokenSender { use starknet::{get_caller_address, ContractAddress, get_contract_address};

use crate::erc20::erc20::{IERC20Dispatcher, IERC20DispatcherTrait};

use super::TransferRequest;


#[event]
#[derive(Drop, starknet::Event)]
enum Event {
    TokensSent: TokensSent,
}
#[derive(Drop, starknet::Event)]
struct TokensSent {
    token_address: ContractAddress,
    recipients: felt252,
}


#[constructor]
fn constructor(ref self: ContractState,) {}

#[storage]
struct Storage {}

#[abi(embed_v0)]
impl TokenSender of super::ITokenSender<ContractState> {
    fn multisend(
        self: @ContractState,
        token_address: ContractAddress,
        transfer_list: Array<TransferRequest>
    ) {
        let erc20 = IERC20Dispatcher { contract_address: token_address };

        let mut total_amount: u256 = 0;

        for t in transfer_list.span() {
            total_amount += *t.amount;
        };

        erc20.transfer_from(get_caller_address(), get_contract_address(), total_amount);

        for t in transfer_list.span() {
            erc20.transfer(*t.recipient, *t.amount);
        };
    }
}

} ```

Scarb toml example This is and example of a modern Scarb toml. It uses openzeppelin libraries from the scarbs.xyz registry, 0.20.0 is the latest version ```toml [package] name = "token_sender" version = "0.5.0" license-file = "LICENSE" edition = "2024_07"

See more keys and their definitions at https://docs.swmansion.com/scarb/docs/reference/manifes

[[target.starknet-contract]] sierra = true casm=false

[dependencies] openzeppelin_token = "0.20.0" starknet = "2.9.0"

[dev-dependencies] snforge_std = "0.35.0" ```

Importing a component Importing a component requires a few rules

• Adding the component with the component macro Example: ```cairo component!(path: ERC20Component, storage: erc20, event: ERC20Event); ```

• Adding the storage to the contract storage Example: ```cairo #[storage] struct Storage { #[substorage(v0)] erc20: ERC20Component::Storage } ```

• Adding the events to the contract events: ```cairo #[event] #[derive(Drop, starknet::Event)] enum Event { ERC20Event: ERC20Component::Event } ```

If there are internal implementation in the component, they need to be seperatly imported as Impl Example: ```cairo #[abi(embed_v0)] impl ERC20MixinImpl = ERC20Component::ERC20MixinImpl<ContractState>; impl ERC20InternalImpl = ERC20Component::InternalImpl<ContractState>; ```

Full example of adding an ERC20 component from OpenZeppelin (OZ) ```cairo #[starknet::contract] mod MyERC20Token { use openzeppelin_token::erc20::{ERC20Component, ERC20HooksEmptyImpl}; use starknet::ContractAddress;

component!(path: ERC20Component, storage: erc20, event: ERC20Event);

// ERC20 Mixin
#[abi(embed_v0)]
impl ERC20MixinImpl = ERC20Component::ERC20MixinImpl<ContractState>;
impl ERC20InternalImpl = ERC20Component::InternalImpl<ContractState>;

#[storage]
struct Storage {
    #[substorage(v0)]
    erc20: ERC20Component::Storage
}

#[event]
#[derive(Drop, starknet::Event)]
enum Event {
    #[flat]
    ERC20Event: ERC20Component::Event
}

#[constructor]
fn constructor(
    ref self: ContractState,
    name: ByteArray,
    symbol: ByteArray,
    fixed_supply: u256,
    recipient: ContractAddress
) {
    self.erc20.initializer(name, symbol);
    self.erc20.mint(recipient, fixed_supply);
}

} ```

lib.cairo example

This is an example of a lib.cairo file, it is a mandatory file in src lib. It specified the modules that are available in the library. In this case there is erc20 module and a token sender module, as with the implementation seen above.

```cairo pub mod erc20; pub mod token_sender; ```

Implementation of interface Component exampleImplementations of the interface start with the attribute ` ```cairo #[abi(embed_v0)] ```

Testing and Deployment:

• Develop comprehensive unit and integration tests
• Use Starknet's testing frameworks, Starknet-Foundry
• Simulate on-chain environments
• Perform thorough testnet validation before mainnet deployment
• Implement CI/CD pipelines for automated testing

Tests are usually added in the `./tests` directory of the project, and are also cairo files

Tests are annotated with the `#[test]` annotation

Tests use the `snforge_std` library and its cheatcodes to perform tests. The test file needs to import the module it is testing Example: ```cairo

use snforge_std::{declare, cheat_caller_address, ContractClassTrait, CheatSpan, DeclareResultTrait};

use snforge_std::trace::get_call_trace;

use starknet::{contract_address_const, ContractAddress};

use token_sender::erc20::erc20::{IERC20Dispatcher, IERC20DispatcherTrait};

use token_sender::token_sender::{ITokenSenderDispatcher, ITokenSenderDispatcherTrait}; use token_sender::token_sender::TransferRequest; ```

And example of a setup function, delcaring and deploying and ERC20 contract, and a TokenSender contract ```cairo fn setup() -> (ContractAddress, ContractAddress) { let erc20_class_hash = declare("MockERC20").unwrap().contract_class(); // let account: ContractAddress = get_contract_address();

let account: ContractAddress = contract_address_const::<1>();
// let account: ContractAddress = get_contract_address();

let mut calldata = ArrayTrait::new();
INITIAL_SUPPLY.serialize(ref calldata);
account.serialize(ref calldata);

let (erc20_address, _) = erc20_class_hash.deploy(@calldata).unwrap();

let token_sender_class_hash = declare("TokenSender").unwrap().contract_class();
// let account: ContractAddress = get_contract_address();

let mut calldata = ArrayTrait::new();

let (token_sender_address, _) = token_sender_class_hash.deploy(@calldata).unwrap();

(erc20_address, token_sender_address)

} ```

Here is an example of a test using the return values of the setup function above, to test the functionality of the TokenSender contract ```cairo #[test] fn test_multisend() { let (erc20_address, token_sender_address) = setup(); let erc20 = IERC20Dispatcher { contract_address: erc20_address };

let account: ContractAddress = contract_address_const::<1>();

assert(erc20.balance_of(account) == INITIAL_SUPPLY, 'Balance should be > 0');

cheat_caller_address(erc20_address, account, CheatSpan::TargetCalls(1));

let transfer_value: u256 = 100;
erc20.approve(token_sender_address, transfer_value * 2 - 1);

assert(
    erc20.allowance(account, token_sender_address) == transfer_value * 2,
    'Allowance not
    set',
);

let balance = erc20.balance_of(account);
println!("Balance {}", balance);

// Send tokens via multisend
let token_sender = ITokenSenderDispatcher { contract_address: token_sender_address };
let dest1: ContractAddress = contract_address_const::<2>();
let dest2: ContractAddress = contract_address_const::<3>();
let request1 = TransferRequest { recipient: dest1, amount: transfer_value };
let request2 = TransferRequest { recipient: dest2, amount: transfer_value };

let mut transfer_list = ArrayTrait::<TransferRequest>::new();
transfer_list.append(request1);
transfer_list.append(request2);

// need to also cheat the token sender
cheat_caller_address(token_sender_address, account, CheatSpan::TargetCalls(1));
token_sender.multisend(erc20_address, transfer_list);

let balance_after = erc20.balance_of(dest1);
assert(balance_after == transfer_value, 'Balance should be > 0');
let balance_after = erc20.balance_of(dest2);
assert(balance_after == transfer_value, 'Balance should be > 0');

} ``` `, author: { name: "amanusk", url: "https://x.com/amanusk_", avatar: "https://avatars.githubusercontent.com/u/7280933?v=4", }, }, ];