Python practical guide to writing Ethereum smart contract code

In this era of rapid change, blockchain technology has become an integral part of our lives.

Python, as a powerful programming language, provides developers with the ability to write smart contracts.

This article will take you to learn how to use Python to write Ethereum smart contract code, and share some practical tips and suggestions.

Whether you are a novice programmer or an experienced developer, you can get valuable information and inspiration from it.

Let's explore this potential technology field together and start a new journey!

I. Environmental preparation.

Before we start writing Ethereum smart contracts, we need to do some preparatory work.

First, make sure you have Python and related development tools installed.

1. Install Python.

If you have not installed Python, you can download and install the latest version of Python from [Python official website] (https://www.python.org/).

2. Install the Web3.py library.

Web 3.py is a Python library for interacting with the Ethereum blockchain.

You can install it with the pip command:

pip install web3

3. Install the Solidity compiler.

In order to compile Solidity smart contracts, you need to install solc (Solidity compiler).

You can install solc using the following command:

pip install py-solc-x

4. Install Ganache.

Ganache is a personal blockchain for testing Ethereum smart contracts locally.

You can download and install it from [Ganache official website] (https://trufflesuite.com/ganache/).

II. Write smart contracts.

We will use the Solidity language to write a simple smart contract.

Solidity is a high-level programming language designed specifically for the Ethereum Virtual Machine (EVM).

1. Create a smart contract file.

Create a directory in your project called SimpleStorage.solFile, and write the following code in it:

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

contract SimpleStorage {
    uint256 private storedData;

    function set(uint256 x) public {
        storedData = x;
    }

    function get() public view returns (uint256) {
        return storedData;
    }
}

2. Compile smart contracts.

Next, we need to compile this smart contract.

This step can be done using the solc compiler.

The following is a simple Python script for compiling Solidity files:

from solcx import compile_standard, install_solc
import json

# 安装solc编译器
install_solc('0.8.0')

# 读取Solidity文件内容
with open('SimpleStorage.sol', 'r') as file:
    simple_storage_file = file.read()

# 编译Solidity文件
compiled_sol = compile_standard({
    "language": "Solidity",
    "sources": {"SimpleStorage.sol": {"content": simple_storage_file}},
    "settings": {
        "outputSelection": {
            "*": {"*": ["abi", "metadata", "evm.bytecode", "evm.sourceMap"]}
        }
    },
}, solc_version='0.8.0')

# 将编译结果保存到JSON文件中
with open('compiled_code.json', 'w') as outfile:
    json.dump(compiled_sol, outfile)

III. Deploy smart contracts.

After successfully compiling the smart contract, we need to deploy it to the Ethereum network.

Here we use Ganache as the local blockchain network.

1. Start Ganache.

Open the Ganache application and start a new workspace.

Note the displayed RPC URL (for example: http://127.0.0.1:7545).

2. Deploy smart contracts.

Next, we write a Python script to deploy smart contracts:

from web3 import Web3
import json

# 连接到Ganache本地区块链网络
w3 = Web3(Web3.HTTPProvider('http://127.0.0.1:7545'))
assert w3.isConnected(), "Failed to connect to Ganache"

# 设置默认账户
w3.eth.defaultAccount = w3.eth.accounts[0]

# 读取编译后的智能合约ABI和字节码
with open('compiled_code.json', 'r') as file:
    compiled_sol = json.load(file)
    contract_abi = compiled_sol['contracts']['SimpleStorage.sol']['SimpleStorage']['abi']
    contract_bytecode = compiled_sol['contracts']['SimpleStorage.sol']['SimpleStorage']['evm']['bytecode']['object']

# 创建合约对象
SimpleStorage = w3.eth.contract(abi=contract_abi, bytecode=contract_bytecode)

# 部署合约
tx_hash = SimpleStorage.constructor().transact()
tx_receipt = w3.eth.waitForTransactionReceipt(tx_hash)
print(f'Contract deployed at address: {tx_receipt.contractAddress}')

3. Interact with smart contracts.

After deployment, we can interact with smart contracts.

The following is a simple example of how to call a smart contract setSumgetMethod:

# 创建合约实例
contract_address = tx_receipt.contractAddress
simple_storage = w3.eth.contract(address=contract_address, abi=contract_abi)

# 调用set方法设置值
tx_hash = simple_storage.functions.set(42).transact()
w3.eth.waitForTransactionReceipt(tx_hash)
print('Value set to 42')

# 调用get方法获取值
stored_value = simple_storage.functions.get().call()
print(f'Stored value is: {stored_value}')

IV. Summary and Suggestions.

Through the introduction of this article, you should have mastered the basic steps of how to write, compile and deploy Ethereum smart contracts in Python.

In actual development, you may encounter various problems and challenges, but don't be discouraged.

Here are some practical suggestions: 1. # In-depth learning Solidity #: Mastering the Solidity language is the key to writing efficient smart contracts.

It is recommended to read official documentation and tutorials for more advanced features and best practices.

2. # Familiar with Web3.py #: Web3.py is an important tool for interacting with the Ethereum blockchain.

Taking the time to familiarize yourself with its APIs and functions can help you develop blockchain applications more efficiently.

3. # Test and Debug #: Fully test on local blockchain networks (such as Ganache) to ensure the functionality and security of smart contracts.

Use debugging tools and logging to find and resolve problems.

4. # Continuous Learning #: Blockchain technology and the Ethereum ecosystem are constantly evolving, keeping learning and paying attention to the latest technological developments can help you stay competitive.

I hope this article can help you get started with the development of Ethereum smart contracts.

I wish you more achievements on the road of blockchain development!