Ethereum 実習 / Practicing Ethereum

2018年10月31日(水)、ブロックチェーンハブ主催で開催されたブロックチェーンアカデミー「【ハンズオン】スマートコントラクトプログラミング(2) イーサリアム実習」にて使用したスライドです。

Transcript

1. (2) CSO / SFC ( https://speakerdeck.com/ks91 ) ks91@blockchainhub.co.jp — (2) — 2018-10-31 – p.1/37
2. 1. 2. 3. 4. 5. — (2) — 2018-10-31 – p.2/37
3. 1. : ERC20 2. : 3. : — (2) — 2018-10-31 – p.3/37
4. 1. : ERC20 ERC20 — (2) — 2018-10-31 – p.4/37
5. BcH-smart-contract-programming.zip solidity 0.4.21 contracts tests ( ) — (2) — 2018-10-31 – p.5/37
6. Solidity JavaScript ( , ) (constructor) ( ) ( ) Ether — (2) — 2018-10-31 – p.6/37
7. pragma solidity ˆ0.4.24; contract MyToken { ( ) : (EVM ) : constructor (...) public { /* */ : } function MyToken(...) { /* ( ) */ : } : } constructor C (/* */ // ) — (2) — 2018-10-31 – p.7/37
8. ERC20 ERC (Ethereum Request for Comment) 20 https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md contract ERC20 { function totalSupply() constant returns (uint totalSupply); function balanceOf(address _owner) constant returns (uint balance); function transfer(address _to, uint _value) returns (bool success); function transferFrom(address _from, address _to, uint _value) returns (bool success); function approve(address _spender, uint _value) returns (bool success); function allowance(address _owner, address _spender) constant returns (uint remaining); event Transfer(address indexed _from, address indexed _to, uint _value); event Approval(address indexed _owner, address indexed _spender, uint _value); } name/ , symbol/ , decimals/ approve allowance ERC223 ( ), ERC721 (Non-Fungible) — (2) — 2018-10-31 – p.8/37
9. MyToken string public _name; string public _symbol; uint8 public _decimals; mapping (address => uint256) public _balanceOf; uint256 _totalSupply; _name, _symbol _decimals : 2 100 1.00 mapping _balanceOf ‘_’ Solidity . . . — (2) — 2018-10-31 – p.9/37
10. MyToken event Transfer(address indexed from, address indexed to, uint256 value); indexed (3 ) MyToken function Transfer() — (2) — 2018-10-31 – p.10/37
11. MyToken constructor (uint256 supply, string name, string symbol, uint8 decimals) public { if (supply == 0) { supply = 1000000; /* supply 1,000,000 */ } _totalSupply = supply; _balanceOf[msg.sender] = supply; _name = name; _symbol = symbol; _decimals = decimals; } msg.sender supply — (2) — 2018-10-31 – p.11/37
12. MyToken balanceOf() function balanceOf(address tokenOwner) external view returns (uint256) { return _balanceOf[tokenOwner]; } — (2) — 2018-10-31 – p.12/37
13. MyToken transfer() function transfer(address to, uint256 value) external returns (bool) { require(value <= _balanceOf[msg.sender]); /* */ require(_balanceOf[to] + value >= _balanceOf[to]); /* */ _balanceOf[msg.sender] -= value; _balanceOf[to] += value; Transfer(msg.sender, to, value); return true; } require (function ) OpenZeppelin https://openzeppelin.org — (2) — 2018-10-31 – p.13/37
14. (1) import pytest @pytest.fixture() def token_contract(chain): TokenFactory = chain.provider.get_contract_factory(’MyToken’) deploy_txid = TokenFactory.deploy(args=[ 0, "BcH Coin", "BcH", 0, ]) contract_address = chain.wait.for_contract_address(deploy_txid) return TokenFactory(address=contract_address) populus — (2) — 2018-10-31 – p.14/37
15. (2) def test_my_token(token_contract, chain): account0 = chain.web3.eth.accounts[0] account1 = chain.web3.eth.accounts[1] assert token_contract.call().balanceOf(account0) == 1000000 assert token_contract.call().balanceOf(account1) == 0 txid = token_contract.transact().transfer(account1, 10) chain.wait.for_receipt(txid) assert token_contract.call().balanceOf(account0) == 999990 assert token_contract.call().balanceOf(account1) == 10 account0 coinbase account1 account0 account1 10BcH — (2) — 2018-10-31 – p.15/37
16. $ py.test -k test_my_token.py — (2) — 2018-10-31 – p.16/37
17. 2. — (2) — 2018-10-31 – p.17/37
18. (m2 ) 1 1 — (2) — 2018-10-31 – p.18/37
19. IndivisibleAsset string public _name; string public _symbol; uint256 public _quantity; address public _owner; _name ( ) _symbol _quantity (m2 ) _owner — (2) — 2018-10-31 – p.19/37
20. IndivisibleAsset event Transfer(address indexed from, address indexed to); from to — (2) — 2018-10-31 – p.20/37
21. IndivisibleAsset constructor (string name, string symbol, uint256 quantity) public { _name = name; _symbol = symbol; _quantity = quantity; _owner = msg.sender; } — (2) — 2018-10-31 – p.21/37
22. IndivisibleAsset getOwner() function getOwner() external view returns (address) { return (_owner); } — (2) — 2018-10-31 – p.22/37
23. IndivisibleAsset transfer() function transfer(address to) external returns (bool) { require(_owner == msg.sender); _owner = to; Transfer(msg.sender, to); return true; } ( / ) $ populus compile — (2) — 2018-10-31 – p.23/37
24. (1) import pytest @pytest.fixture() def asset_contract(chain): AssetFactory = chain.provider.get_contract_factory(’IndivisibleAsset’) deploy_txid = AssetFactory.deploy(args=[ "5322 Endo, Fujisawa", "mˆ2", 300, ]) contract_address = chain.wait.for_contract_address(deploy_txid) return AssetFactory(address=contract_address) SFC (300m2 ) — (2) — 2018-10-31 – p.24/37
25. (2) def test_indivisible_assset(asset_contract, chain): account0 = chain.web3.eth.accounts[0] account1 = chain.web3.eth.accounts[1] assert asset_contract.call().getOwner() == account0 txid = asset_contract.transact().transfer(account1) chain.wait.for_receipt(txid) assert asset_contract.call().getOwner() == account1 account0 account1 — (2) — 2018-10-31 – p.25/37
26. $ py.test -k test_indivisible_asset.py — (2) — 2018-10-31 – p.26/37
27. 3. — (2) — 2018-10-31 – p.27/37
28. transfer settle, retrieve asset, retrieve token 3 — (2) — 2018-10-31 – p.28/37
29. 1. ( ) 2. ( ) 3. ( ) — (2) — 2018-10-31 – p.29/37
30. OneTimeEscrow settle() function settle() public returns (bool) { require(_token.balanceOf(this) >= _price); /* this */ require(_asset.getOwner() == address(this)); _token.transfer(_seller , _price); _asset.transfer(_buyer); Settled(); /* */ return true; } settle() transfer ( / ) $ populus compile solidity 0.4.21 — (2) — 2018-10-31 – p.30/37
31. (1) import pytest @pytest.fixture() def token_contract(chain): . . . @pytest.fixture() def asset_contract(chain): . . . — (2) — 2018-10-31 – p.31/37
32. (2) def test_one_time_escrow(token_contract, asset_contract, chain): account0 = chain.web3.eth.accounts[0] account1 = chain.web3.eth.accounts[1] txid = chain.web3.eth.sendTransaction({ ’from’: account0, ’to’: account1, ’value’: chain.web3.toWei(1, "ether") }) chain.wait.for_receipt(txid) txid = token_contract.transact().transfer(account1, 300) chain.wait.for_receipt(txid) account0 account1 1Ether 300BcH 300BcH TX — (2) — 2018-10-31 – p.32/37
33. (3) EscrowFactory = chain.provider.get_contract_factory(’OneTimeEscrow’) txid = EscrowFactory.deploy(args=[ token_contract.address, account1, asset_contract.address, account0, 300, ]) contract_address = chain.wait.for_contract_address(txid) EscrowFactory.address = contract_address; account1 account0 300BcH — (2) — 2018-10-31 – p.33/37
34. (4) txid = token_contract.transact({ ’from’: account1 }).transfer(contract_address, 300) chain.wait.for_receipt(txid) txid = asset_contract.transact().transfer(contract_address) chain.wait.for_receipt(txid) assert token_contract.call().balanceOf(account0) == 999700 assert token_contract.call().balanceOf(account1) == 0 assert token_contract.call().balanceOf(contract_address) == 300 assert asset_contract.call().getOwner() == contract_address account1 300BcH account0 — (2) — 2018-10-31 – p.34/37
35. (5) txid = EscrowFactory.transact().settle(); chain.wait.for_receipt(txid) assert token_contract.call().balanceOf(account0) == 1000000 assert token_contract.call().balanceOf(account1) == 0 assert token_contract.call().balanceOf(contract_address) == 0 assert asset_contract.call().getOwner() == account1 settle() — (2) — 2018-10-31 – p.35/37
36. $ py.test -k test_one_time_escrow.py : settle() — (2) — 2018-10-31 – p.36/37
37. BBc-1 1. BBc-1 2. BBc-1 3. 4. Ethereum ( ) — (2) — 2018-10-31 – p.37/37