Smart Contract Development

Introduction to Smart Contracts

Smart contracts are self-executing contracts with the terms of the agreement directly written into code. On verychain, smart contracts are written in Solidity and executed on the EVM.

Development Environment Setup

Required Tools

1. Node.js: v18.0.0 or higher

2. Truffle/Hardhat/Foundry: Development framework

3. MetaMask: Browser wallet

4. Solidity: ^0.8.0

IDE Setup

• Visual Studio Code with Solidity extension

• Remix: Online IDE for quick testing

Writing Smart Contracts

Basic Contract Structure

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract ExampleContract {
    // State variables
    address public owner;
    uint256 public value;

    // Constructor
    constructor() {
        owner = msg.sender;
    }

    // Functions
    function setValue(uint256 _value) public {
        require(msg.sender == owner, "Not authorized");
        value = _value;
    }
}

Best Practices

Security

1. Access Control

   • Use OpenZeppelin's AccessControl

   • Implement proper authorization checks

   • Use multi-signature wallets for critical operations

2. Reentrancy Protection

   • Use checks-effects-interactions pattern

   • Implement reentrancy guards

3. Input Validation

   • Validate all external inputs

   • Use SafeMath for arithmetic operations

   • Check for zero addresses

Gas Optimization

1. Storage Optimization

   • Pack variables efficiently

   • Use appropriate data types

   • Minimize storage operations

2. Function Optimization

   • Batch operations when possible

   • Use events for off-chain tracking

   • Optimize loops and conditions

Testing

Unit Testing

const ExampleContract = artifacts.require("ExampleContract");

contract("ExampleContract", accounts => {
  it("should set the value correctly", async () => {
    const instance = await ExampleContract.deployed();
    await instance.setValue(42);
    const value = await instance.value();
    assert.equal(value, 42);
  });
});

Test Coverage

• Aim for 100% test coverage

• Test edge cases

• Use different testing frameworks (Truffle, Hardhat)

Deployment

Network Configuration

module.exports = {
  networks: {
    very: {
      url: "RPC_ENDPOINT",
      chainId: CHAIN_ID,
      accounts: ["PRIVATE_KEY"]
    }
  }
};

Deployment Steps

1. Compile contracts

2. Run tests

3. Deploy to testnet

4. Verify contract code

5. Deploy to mainnet

Contract Verification

Verification Process

1. Deploy contract

2. Get contract address

3. Verify source code on block explorer

4. Test verified contract

Monitoring and Maintenance

Contract Monitoring

• Track contract events

• Monitor gas usage

• Set up alerts for critical events

Upgrade Patterns

• Use proxy patterns for upgradeable contracts

• Implement proper versioning

• Plan for contract upgrades