Solidity基礎学習25日目(ERC20 vs ERC777, ERC721 vs ERC1155)

Solidity基礎学習 - ERC規格の比較分析

日付: 2025年9月22日
学習内容: ERC20とERC777の共通点・相違点、ERC721とERC1155の共通点・相違点について

1. ERC規格の概要

1.1 ERC規格とは

Ethereum Request for Comments（ERC）は、Ethereumネットワーク上での標準的なスマートコントラクトの実装方法を定義する規格です。これらの規格により、異なるプロジェクト間での互換性と相互運用性が確保されます。

主要なERC規格：

• ERC20: 同質化トークン（Fungible Token）の標準
• ERC777: ERC20の改良版、より高度な機能を持つ同質化トークン
• ERC721: 非同質化トークン（NFT）の標準
• ERC1155: マルチトークン標準、同質化と非同質化トークンを統合

1.2 トークンの種類

// 同質化トークン（Fungible Token）
// - 同じ価値を持つ、交換可能なトークン
// - 例：ETH、USDC、DAI

// 非同質化トークン（Non-Fungible Token）
// - 固有の価値を持つ、交換不可能なトークン
// - 例：アート作品、ゲームアイテム、デジタル資産

2. ERC20とERC777の比較分析

2.1 ERC20の基本構造

ERC20の必須関数

interface IERC20 {
    // 必須関数
    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address to, uint256 amount) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function approve(address spender, uint256 amount) external returns (bool);
    function transferFrom(address from, address to, uint256 amount) external returns (bool);
    
    // 必須イベント
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

ERC20の実装例

contract SimpleERC20 is IERC20 {
    mapping(address => uint256) private _balances;
    mapping(address => mapping(address => uint256)) private _allowances;
    
    uint256 private _totalSupply;
    string public name;
    string public symbol;
    uint8 public decimals;
    
    constructor(string memory _name, string memory _symbol, uint8 _decimals) {
        name = _name;
        symbol = _symbol;
        decimals = _decimals;
        _totalSupply = 1000000 * 10**_decimals;
        _balances[msg.sender] = _totalSupply;
    }
    
    function transfer(address to, uint256 amount) public override returns (bool) {
        _balances[msg.sender] -= amount;
        _balances[to] += amount;
        emit Transfer(msg.sender, to, amount);
        return true;
    }
    
    function approve(address spender, uint256 amount) public override returns (bool) {
        _allowances[msg.sender][spender] = amount;
        emit Approval(msg.sender, spender, amount);
        return true;
    }
    
    function transferFrom(address from, address to, uint256 amount) public override returns (bool) {
        _allowances[from][msg.sender] -= amount;
        _balances[from] -= amount;
        _balances[to] += amount;
        emit Transfer(from, to, amount);
        return true;
    }
}

2.2 ERC777の基本構造

ERC777の拡張機能

interface IERC777 {
    // ERC20の機能を継承
    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address to, uint256 amount) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function approve(address spender, uint256 amount) external returns (bool);
    function transferFrom(address from, address to, uint256 amount) external returns (bool);
    
    // ERC777の追加機能
    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function granularity() external view returns (uint256);
    function defaultOperators() external view returns (address[] memory);
    function isOperatorFor(address operator, address tokenHolder) external view returns (bool);
    function authorizeOperator(address operator) external;
    function revokeOperator(address operator) external;
    function send(address to, uint256 amount, bytes calldata userData) external;
    function operatorSend(address from, address to, uint256 amount, bytes calldata userData, bytes calldata operatorData) external;
    function burn(uint256 amount, bytes calldata data) external;
    function operatorBurn(address from, uint256 amount, bytes calldata data, bytes calldata operatorData) external;
    
    // ERC777のイベント
    event Sent(address indexed operator, address indexed from, address indexed to, uint256 amount, bytes data, bytes operatorData);
    event Minted(address indexed operator, address indexed to, uint256 amount, bytes data, bytes operatorData);
    event Burned(address indexed operator, address indexed from, uint256 amount, bytes data, bytes operatorData);
    event AuthorizedOperator(address indexed operator, address indexed tokenHolder);
    event RevokedOperator(address indexed operator, address indexed tokenHolder);
}

2.3 ERC20とERC777の共通点

共通の機能

// 1. 基本的なトークン機能
function totalSupply() external view returns (uint256);
function balanceOf(address account) external view returns (uint256);
function transfer(address to, uint256 amount) external returns (bool);

// 2. 承認システム
function allowance(address owner, address spender) external view returns (uint256);
function approve(address spender, uint256 amount) external returns (bool);
function transferFrom(address from, address to, uint256 amount) external returns (bool);

// 3. 基本的なイベント
event Transfer(address indexed from, address indexed to, uint256 value);
event Approval(address indexed owner, address indexed spender, uint256 value);

共通の設計思想

// 1. 同質化トークンの特性
// - 同じ価値を持つ
// - 交換可能
// - 数量で管理

// 2. 残高管理システム
mapping(address => uint256) private _balances;

// 3. 承認システム
mapping(address => mapping(address => uint256)) private _allowances;

2.4 ERC20とERC777の相違点

主要な相違点

機能	ERC20	ERC777
基本機能	基本的なトークン機能のみ	ERC20の機能 + 拡張機能
オペレーター機能	なし	あり（第三者による操作可能）
フック機能	なし	あり（送金前後の処理）
データ送信	なし	あり（送金時にデータ添付可能）
バーン機能	なし（実装次第）	標準化されたバーン機能
メタデータ	オプション	必須（name, symbol, granularity）

オペレーター機能の違い

// ERC20: 承認ベースのシステム
function approve(address spender, uint256 amount) external returns (bool);
function transferFrom(address from, address to, uint256 amount) external returns (bool);

// ERC777: オペレーターベースのシステム
function authorizeOperator(address operator) external;
function revokeOperator(address operator) external;
function operatorSend(address from, address to, uint256 amount, bytes calldata userData, bytes calldata operatorData) external;

フック機能の違い

// ERC20: フック機能なし
function transfer(address to, uint256 amount) external returns (bool);

// ERC777: フック機能あり
interface IERC777Recipient {
    function tokensReceived(address operator, address from, address to, uint256 amount, bytes calldata userData, bytes calldata operatorData) external;
}

interface IERC777Sender {
    function tokensToSend(address operator, address from, address to, uint256 amount, bytes calldata userData, bytes calldata operatorData) external;
}

2.5 ERC777の実装例

contract AdvancedERC777 is IERC777 {
    mapping(address => uint256) private _balances;
    mapping(address => mapping(address => bool)) private _operators;
    mapping(address => mapping(address => uint256)) private _allowances;
    
    uint256 private _totalSupply;
    string private _name;
    string private _symbol;
    uint256 private _granularity;
    address[] private _defaultOperators;
    
    constructor(string memory name_, string memory symbol_, uint256 granularity_) {
        _name = name_;
        _symbol = symbol_;
        _granularity = granularity_;
        _totalSupply = 1000000 * granularity_;
        _balances[msg.sender] = _totalSupply;
    }
    
    function send(address to, uint256 amount, bytes calldata userData) external override {
        _send(msg.sender, msg.sender, to, amount, userData, "", true);
    }
    
    function operatorSend(address from, address to, uint256 amount, bytes calldata userData, bytes calldata operatorData) external override {
        require(isOperatorFor(msg.sender, from), "ERC777: caller is not an operator");
        _send(msg.sender, from, to, amount, userData, operatorData, true);
    }
    
    function _send(address operator, address from, address to, uint256 amount, bytes memory userData, bytes memory operatorData, bool requireReceptionAck) internal {
        require(from != address(0), "ERC777: send from the zero address");
        require(to != address(0), "ERC777: send to the zero address");
        
        // 送信前フック
        _callTokensToSend(operator, from, to, amount, userData, operatorData);
        
        _balances[from] -= amount;
        _balances[to] += amount;
        
        emit Sent(operator, from, to, amount, userData, operatorData);
        
        // 受信後フック
        _callTokensReceived(operator, from, to, amount, userData, operatorData, requireReceptionAck);
    }
    
    function _callTokensToSend(address operator, address from, address to, uint256 amount, bytes memory userData, bytes memory operatorData) private {
        address implementer = _ERC1820_REGISTRY.getInterfaceImplementer(from, _TOKENS_SENDER_INTERFACE_HASH);
        if (implementer != address(0)) {
            IERC777Sender(implementer).tokensToSend(operator, from, to, amount, userData, operatorData);
        }
    }
    
    function _callTokensReceived(address operator, address from, address to, uint256 amount, bytes memory userData, bytes memory operatorData, bool requireReceptionAck) private {
        address implementer = _ERC1820_REGISTRY.getInterfaceImplementer(to, _TOKENS_RECIPIENT_INTERFACE_HASH);
        if (implementer != address(0)) {
            IERC777Recipient(implementer).tokensReceived(operator, from, to, amount, userData, operatorData);
        } else if (requireReceptionAck) {
            require(!to.isContract(), "ERC777: token recipient contract has no implementer for ERC777TokensRecipient");
        }
    }
}

3. ERC721とERC1155の比較分析

3.1 ERC721の基本構造

ERC721の必須関数

interface IERC721 {
    // 必須関数
    function balanceOf(address owner) external view returns (uint256 balance);
    function ownerOf(uint256 tokenId) external view returns (address owner);
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external;
    function safeTransferFrom(address from, address to, uint256 tokenId) external;
    function transferFrom(address from, address to, uint256 tokenId) external;
    function approve(address to, uint256 tokenId) external;
    function setApprovalForAll(address operator, bool approved) external;
    function getApproved(uint256 tokenId) external view returns (address operator);
    function isApprovedForAll(address owner, address operator) external view returns (bool);
    
    // 必須イベント
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);
}

ERC721の実装例

contract SimpleERC721 is IERC721 {
    mapping(uint256 => address) private _owners;
    mapping(address => uint256) private _balances;
    mapping(uint256 => address) private _tokenApprovals;
    mapping(address => mapping(address => bool)) private _operatorApprovals;
    
    string public name;
    string public symbol;
    
    constructor(string memory _name, string memory _symbol) {
        name = _name;
        symbol = _symbol;
    }
    
    function mint(address to, uint256 tokenId) public {
        require(to != address(0), "ERC721: mint to the zero address");
        require(!_exists(tokenId), "ERC721: token already minted");
        
        _balances[to] += 1;
        _owners[tokenId] = to;
        
        emit Transfer(address(0), to, tokenId);
    }
    
    function transferFrom(address from, address to, uint256 tokenId) public override {
        require(_isApprovedOrOwner(msg.sender, tokenId), "ERC721: transfer caller is not owner nor approved");
        
        _transfer(from, to, tokenId);
    }
    
    function _transfer(address from, address to, uint256 tokenId) internal {
        require(ownerOf(tokenId) == from, "ERC721: transfer from incorrect owner");
        require(to != address(0), "ERC721: transfer to the zero address");
        
        _approve(address(0), tokenId);
        
        _balances[from] -= 1;
        _balances[to] += 1;
        _owners[tokenId] = to;
        
        emit Transfer(from, to, tokenId);
    }
}

3.2 ERC1155の基本構造

ERC1155の必須関数

interface IERC1155 {
    // 必須関数
    function safeTransferFrom(address from, address to, uint256 id, uint256 amount, bytes calldata data) external;
    function safeBatchTransferFrom(address from, address to, uint256[] calldata ids, uint256[] calldata amounts, bytes calldata data) external;
    function balanceOf(address account, uint256 id) external view returns (uint256);
    function balanceOfBatch(address[] calldata accounts, uint256[] calldata ids) external view returns (uint256[] memory);
    function setApprovalForAll(address operator, bool approved) external;
    function isApprovedForAll(address account, address operator) external view returns (bool);
    
    // 必須イベント
    event TransferSingle(address indexed operator, address indexed from, address indexed to, uint256 id, uint256 value);
    event TransferBatch(address indexed operator, address indexed from, address indexed to, uint256[] ids, uint256[] values);
    event ApprovalForAll(address indexed account, address indexed operator, bool approved);
    event URI(string value, uint256 indexed id);
}

ERC1155の実装例

contract MultiTokenERC1155 is IERC1155 {
    mapping(uint256 => mapping(address => uint256)) private _balances;
    mapping(address => mapping(address => bool)) private _operatorApprovals;
    mapping(uint256 => string) private _uris;
    
    string private _uri;
    
    constructor(string memory uri_) {
        _setURI(uri_);
    }
    
    function mint(address to, uint256 id, uint256 amount, bytes memory data) public {
        require(to != address(0), "ERC1155: mint to the zero address");
        
        address operator = msg.sender;
        
        _balances[id][to] += amount;
        emit TransferSingle(operator, address(0), to, id, amount);
        
        _doSafeTransferAcceptanceCheck(operator, address(0), to, id, amount, data);
    }
    
    function safeTransferFrom(address from, address to, uint256 id, uint256 amount, bytes calldata data) external override {
        require(from == msg.sender || isApprovedForAll(from, msg.sender), "ERC1155: caller is not owner nor approved");
        require(to != address(0), "ERC1155: transfer to the zero address");
        
        address operator = msg.sender;
        
        uint256 fromBalance = _balances[id][from];
        require(fromBalance >= amount, "ERC1155: insufficient balance for transfer");
        
        _balances[id][from] = fromBalance - amount;
        _balances[id][to] += amount;
        
        emit TransferSingle(operator, from, to, id, amount);
        
        _doSafeTransferAcceptanceCheck(operator, from, to, id, amount, data);
    }
    
    function safeBatchTransferFrom(address from, address to, uint256[] calldata ids, uint256[] calldata amounts, bytes calldata data) external override {
        require(ids.length == amounts.length, "ERC1155: ids and amounts length mismatch");
        require(from == msg.sender || isApprovedForAll(from, msg.sender), "ERC1155: transfer caller is not owner nor approved");
        require(to != address(0), "ERC1155: transfer to the zero address");
        
        address operator = msg.sender;
        
        for (uint256 i = 0; i < ids.length; i++) {
            uint256 id = ids[i];
            uint256 amount = amounts[i];
            
            uint256 fromBalance = _balances[id][from];
            require(fromBalance >= amount, "ERC1155: insufficient balance for transfer");
            _balances[id][from] = fromBalance - amount;
            _balances[id][to] += amount;
        }
        
        emit TransferBatch(operator, from, to, ids, amounts);
        
        _doSafeBatchTransferAcceptanceCheck(operator, from, to, ids, amounts, data);
    }
}

3.3 ERC721とERC1155の共通点

共通の機能

// 1. 基本的なNFT機能
function balanceOf(address owner) external view returns (uint256 balance);
function ownerOf(uint256 tokenId) external view returns (address owner); // ERC721のみ

// 2. 転送機能
function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external;
function transferFrom(address from, address to, uint256 tokenId) external;

// 3. 承認システム
function setApprovalForAll(address operator, bool approved) external;
function isApprovedForAll(address owner, address operator) external view returns (bool);

// 4. 基本的なイベント
event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);
event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

共通の設計思想

// 1. 非同期化トークンの特性
// - 固有の価値を持つ
// - 交換不可能
// - 個別に管理

// 2. 所有者管理システム
mapping(uint256 => address) private _owners; // ERC721
mapping(uint256 => mapping(address => uint256)) private _balances; // ERC1155

// 3. 承認システム
mapping(address => mapping(address => bool)) private _operatorApprovals;

3.4 ERC721とERC1155の相違点

主要な相違点

機能	ERC721	ERC1155
トークン種類	非同質化トークンのみ	同質化・非同質化両対応
数量管理	1個ずつ（固有ID）	複数個（数量指定可能）
バッチ転送	なし	あり（複数トークン同時転送）
URI管理	tokenURI関数	URIイベント
メタデータ	個別のURI	統合されたURIシステム
ガス効率	低い（個別処理）	高い（バッチ処理）

数量管理の違い

// ERC721: 1個ずつの管理
mapping(uint256 => address) private _owners; // 1トークン = 1所有者
function ownerOf(uint256 tokenId) external view returns (address owner);

// ERC1155: 数量での管理
mapping(uint256 => mapping(address => uint256)) private _balances; // トークンID => 所有者 => 数量
function balanceOf(address account, uint256 id) external view returns (uint256);

バッチ処理の違い

// ERC721: 個別処理のみ
function transferFrom(address from, address to, uint256 tokenId) external;
// 複数転送時は個別に実行する必要がある

// ERC1155: バッチ処理対応
function safeBatchTransferFrom(address from, address to, uint256[] calldata ids, uint256[] calldata amounts, bytes calldata data) external;
// 複数トークンを一度に転送可能

URI管理の違い

// ERC721: 個別のURI
function tokenURI(uint256 tokenId) external view returns (string memory) {
    require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");
    return string(abi.encodePacked(_baseURI(), tokenId.toString()));
}

// ERC1155: 統合URIシステム
event URI(string value, uint256 indexed id);
function uri(uint256 id) public view returns (string memory) {
    return string(abi.encodePacked(_uri, id.toString()));
}

4. 実装の詳細比較

4.1 ガス効率の比較

ERC20 vs ERC777

// ERC20: シンプルな実装
function transfer(address to, uint256 amount) external returns (bool) {
    _balances[msg.sender] -= amount;
    _balances[to] += amount;
    emit Transfer(msg.sender, to, amount);
    return true;
}

// ERC777: フック機能付き（ガス消費が多い）
function send(address to, uint256 amount, bytes calldata userData) external {
    _send(msg.sender, msg.sender, to, amount, userData, "", true);
    // フック関数の呼び出しでガス消費が増加
}

ERC721 vs ERC1155

// ERC721: 個別処理（ガス効率が低い）
function batchTransfer(address[] calldata to, uint256[] calldata tokenIds) external {
    for (uint256 i = 0; i < tokenIds.length; i++) {
        transferFrom(msg.sender, to[i], tokenIds[i]);
    }
}

// ERC1155: バッチ処理（ガス効率が高い）
function safeBatchTransferFrom(address from, address to, uint256[] calldata ids, uint256[] calldata amounts, bytes calldata data) external {
    // 複数トークンを一度に処理
}

4.2 セキュリティの比較

フック機能のセキュリティ

// ERC777: フック機能によるセキュリティリスク
contract MaliciousRecipient {
    function tokensReceived(address operator, address from, address to, uint256 amount, bytes calldata userData, bytes calldata operatorData) external {
        // 悪意のあるコードを実行可能
        IERC777(msg.sender).transfer(operator, amount);
    }
}

// 対策: フック機能の適切な実装
contract SecureERC777 {
    function _callTokensReceived(address operator, address from, address to, uint256 amount, bytes memory userData, bytes memory operatorData, bool requireReceptionAck) private {
        address implementer = _ERC1820_REGISTRY.getInterfaceImplementer(to, _TOKENS_RECIPIENT_INTERFACE_HASH);
        if (implementer != address(0)) {
            IERC777Recipient(implementer).tokensReceived(operator, from, to, amount, userData, operatorData);
        } else if (requireReceptionAck) {
            require(!to.isContract(), "ERC777: token recipient contract has no implementer for ERC777TokensRecipient");
        }
    }
}

4.3 互換性の比較

下位互換性

// ERC777はERC20と互換性がある
contract ERC777Compatible is IERC777 {
    // ERC20の関数も実装
    function transfer(address to, uint256 amount) external override returns (bool) {
        send(to, amount, "");
        return true;
    }
    
    function approve(address spender, uint256 amount) external override returns (bool) {
        // ERC20の承認システム
        _allowances[msg.sender][spender] = amount;
        emit Approval(msg.sender, spender, amount);
        return true;
    }
}

// ERC1155はERC721と部分的に互換性がある
contract ERC1155Compatible is IERC1155 {
    // ERC721風の関数を実装
    function ownerOf(uint256 tokenId) external view returns (address) {
        require(balanceOf(msg.sender, tokenId) > 0, "ERC1155: query for nonexistent token");
        return msg.sender; // 簡略化
    }
}

5. 使用場面の比較

5.1 ERC20 vs ERC777の使用場面

ERC20が適している場面

// 1. シンプルなトークン
contract SimpleToken is ERC20 {
    constructor() ERC20("Simple Token", "STK") {
        _mint(msg.sender, 1000000 * 10**18);
    }
}

// 2. 基本的なDeFiプロトコル
contract BasicDeFi {
    IERC20 public token;
    
    function deposit(uint256 amount) external {
        token.transferFrom(msg.sender, address(this), amount);
    }
}

ERC777が適している場面

// 1. 高度な機能が必要なトークン
contract AdvancedToken is ERC777 {
    constructor() ERC777("Advanced Token", "ADV", new address[](0)) {
        _mint(msg.sender, 1000000 * 10**18, "", "");
    }
}

// 2. 自動化された処理
contract AutomatedContract {
    function onTokensReceived(address operator, address from, address to, uint256 amount, bytes calldata userData, bytes calldata operatorData) external {
        // トークン受信時の自動処理
        if (amount > 1000) {
            // 大きな送金時の特別処理
        }
    }
}

5.2 ERC721 vs ERC1155の使用場面

ERC721が適している場面

// 1. アート作品のNFT
contract ArtNFT is ERC721 {
    struct Artwork {
        string title;
        string artist;
        uint256 creationDate;
        string ipfsHash;
    }
    
    mapping(uint256 => Artwork) public artworks;
    
    function mintArtwork(address to, uint256 tokenId, Artwork memory artwork) external {
        _mint(to, tokenId);
        artworks[tokenId] = artwork;
    }
}

// 2. ゲームのキャラクター
contract GameCharacter is ERC721 {
    struct Character {
        uint256 level;
        uint256 experience;
        string name;
        uint256[] abilities;
    }
    
    mapping(uint256 => Character) public characters;
}

ERC1155が適している場面

// 1. ゲームアイテム（複数種類）
contract GameItems is ERC1155 {
    // アイテムID: 1=剣, 2=盾, 3=薬, 4=宝石
    function mintWeapon(address to, uint256 amount) external {
        _mint(to, 1, amount, ""); // 剣をamount個
    }
    
    function mintPotion(address to, uint256 amount) external {
        _mint(to, 3, amount, ""); // 薬をamount個
    }
    
    // バッチで複数アイテムを同時に転送
    function transferItems(address to, uint256[] calldata ids, uint256[] calldata amounts) external {
        safeBatchTransferFrom(msg.sender, to, ids, amounts, "");
    }
}

// 2. マルチトークンプラットフォーム
contract MultiTokenPlatform is ERC1155 {
    // 同質化トークン（ID: 1-100）
    // 非同質化トークン（ID: 101-1000）
    
    function mintFungibleToken(address to, uint256 id, uint256 amount) external {
        require(id >= 1 && id <= 100, "Invalid fungible token ID");
        _mint(to, id, amount, "");
    }
    
    function mintNFT(address to, uint256 id) external {
        require(id >= 101 && id <= 1000, "Invalid NFT ID");
        _mint(to, id, 1, ""); // NFTは数量1
    }
}

6. 学習の成果

6.1 習得した概念

1. ERC規格の理解: 各ERC規格の目的と特徴の把握
2. 同質化トークン: ERC20とERC777の機能比較と実装方法
3. 非同質化トークン: ERC721とERC1155の機能比較と実装方法
4. 互換性: 規格間の互換性と移行方法
5. ガス効率: 各規格のガス消費量と最適化方法
6. セキュリティ: 各規格のセキュリティ考慮事項

6.2 実装スキル

• ERC20トークンの基本的な実装
• ERC777トークンの高度な機能実装
• ERC721NFTの個別管理システム
• ERC1155マルチトークンの統合管理システム
• フック機能の安全な実装
• バッチ処理の効率的な実装

6.3 技術的な理解

• 同質化と非同質化の概念と実装の違い
• オペレーター機能による権限管理
• フック機能による自動化処理
• バッチ処理によるガス効率の向上
• URI管理によるメタデータの統合
• 互換性による既存システムとの連携

7. 今後の学習への応用

7.1 発展的な機能

• ERC1155の拡張: より複雑なマルチトークンシステム
• フック機能の活用: 自動化されたDeFiプロトコル
• メタデータ管理: IPFSとの連携による分散ストレージ
• ガス最適化: バッチ処理による効率化

7.2 実用的な応用

• DeFiプロトコル: トークン標準を活用した金融アプリケーション
• ゲーム開発: NFTとマルチトークンを活用したゲームアイテム
• アートプラットフォーム: デジタルアートのNFT化
• サプライチェーン: トークン化による資産管理

7.3 セキュリティの向上

• フック機能の安全な実装: リエントランシー攻撃への対策
• 権限管理の強化: オペレーター機能の適切な使用
• メタデータの検証: URIの信頼性確保
• バッチ処理の安全性: 配列の境界チェック

---

参考:

• ERC-20 Token Standard
• ERC-777 Token Standard
• ERC-721 Non-Fungible Token Standard
• ERC-1155 Multi Token Standard
• OpenZeppelin Contracts
• Ethereum Improvement Proposals