今一番有名な？EthereumのアプリはおそらくCryptoKittiesかと思いますが、一通りソースコードをみてみたので、解説をしてみようかなと思います。
追記：あまり上手くまとまらなかったです。がとりあえず投稿しておきます。網羅したということで。
一応、ここを見れば、contractのデータが見れるので、ソースもほぼ全てみれます。全部で2000行くらいです。
Contractの構成
結構contract多いです。継承関係を書いていくと、
KittyCore ← KittyMinting ← KittyAuction ← KittyBreeding ← KittyOwnership ← KittyBase, ERC721
KittyBase ← KittyAccessControl
て感じですね。
ERC721
Ethereum Request for Comments 721の略で、non-fungible token（不換トークン）の実装提案です。
公にリリースされたものとしてはCryptoKittiesが初めての実装例だったとか、だったような気がします。
まとめてくれている記事もあるようです。
こちらにも書いてあります
non-fungible tokenというのは、お金のように 5トークン分の価値 = ５トークン分の価値 みたいな状況が常に成り立つものではなく、1トークン = 1トークンみたいな感じで交換できないもの、つまり生き物に紐づいたトークンとかはそれに当たります。トークンAに紐づいた猫Aの価値と、トークンBに紐づいた猫Bの価値はそれぞれ違いますよね。
contract ERC721 {
// Required methods
function totalSupply() public view returns (uint256 total);
function balanceOf(address _owner) public view returns (uint256 balance);
function ownerOf(uint256 _tokenId) external view returns (address owner);
function approve(address _to, uint256 _tokenId) external;
function transfer(address _to, uint256 _tokenId) external;
function transferFrom(address _from, address _to, uint256 _tokenId) external;
// Events
event Transfer(address from, address to, uint256 tokenId);
event Approval(address owner, address approved, uint256 tokenId);
// Optional
// function name() public view returns (string name);
// function symbol() public view returns (string symbol);
// function tokensOfOwner(address _owner) external view returns (uint256[] tokenIds);
// function tokenMetadata(uint256 _tokenId, string _preferredTransport) public view returns (string infoUrl);
// ERC-165 Compatibility (https://github.com/ethereum/EIPs/issues/165)
function supportsInterface(bytes4 _interfaceID) external view returns (bool);
}
解説
totalSupply → トークンの供給量を返す。crytpoKittiesだと猫の数
balanceOf → あるaddressのアカウントがトークンをいくつ持っているかを返す（所有する猫の数）
owneOf → あるトークンのオーナーを返す（猫の所有者）
approve → _toのアドレスに _tokenIdで表されるトークンを所持する権利を与える。トークンの所持者のみ実行できるようにする。
transfer → _to のアドレスに、_tokenIdのトークンを与える。トークンの所有者のみ実行可能。
transferFrom → _from のアドレスから、 _toのアドレスへ、 _tokenIdのトークンの権利を移す。 approveで権利が与えられている場合に実行可能。
event はスキップします
optional の関数について
name → tokenの名前を返す (例： japanToken)
symbol → tokenのシンボルを返す(例： JPT)
tokensOfOwner → _ownerのアドレスが、どのtokenIdの猫を所持しているか返す
tokenMetadata → tokenのメタデータを参照する
KittyAccessControl
contract KittyAccessControl {
// This facet controls access control for CryptoKitties. There are four roles managed here:
//
// - The CEO: The CEO can reassign other roles and change the addresses of our dependent smart
// contracts. It is also the only role that can unpause the smart contract. It is initially
// set to the address that created the smart contract in the KittyCore constructor.
//
// - The CFO: The CFO can withdraw funds from KittyCore and its auction contracts.
//
// - The COO: The COO can release gen0 kitties to auction, and mint promo cats.
//
// It should be noted that these roles are distinct without overlap in their access abilities, the
// abilities listed for each role above are exhaustive. In particular, while the CEO can assign any
// address to any role, the CEO address itself doesn't have the ability to act in those roles. This
// restriction is intentional so that we aren't tempted to use the CEO address frequently out of
// convenience. The less we use an address, the less likely it is that we somehow compromise the
// account.
/// @dev Emited when contract is upgraded - See README.md for updgrade plan
event ContractUpgrade(address newContract);
// The addresses of the accounts (or contracts) that can execute actions within each roles.
address public ceoAddress;
address public cfoAddress;
address public cooAddress;
// @dev Keeps track whether the contract is paused. When that is true, most actions are blocked
bool public paused = false;
/// @dev Access modifier for CEO-only functionality
modifier onlyCEO() {
require(msg.sender == ceoAddress);
_;
}
/// @dev Access modifier for CFO-only functionality
modifier onlyCFO() {
require(msg.sender == cfoAddress);
_;
}
/// @dev Access modifier for COO-only functionality
modifier onlyCOO() {
require(msg.sender == cooAddress);
_;
}
modifier onlyCLevel() {
require(
msg.sender == cooAddress ||
msg.sender == ceoAddress ||
msg.sender == cfoAddress
);
_;
}
/// @dev Assigns a new address to act as the CEO. Only available to the current CEO.
/// @param _newCEO The address of the new CEO
function setCEO(address _newCEO) external onlyCEO {
require(_newCEO != address(0));
ceoAddress = _newCEO;
}
/// @dev Assigns a new address to act as the CFO. Only available to the current CEO.
/// @param _newCFO The address of the new CFO
function setCFO(address _newCFO) external onlyCEO {
require(_newCFO != address(0));
cfoAddress = _newCFO;
}
/// @dev Assigns a new address to act as the COO. Only available to the current CEO.
/// @param _newCOO The address of the new COO
function setCOO(address _newCOO) external onlyCEO {
require(_newCOO != address(0));
cooAddress = _newCOO;
}
/*** Pausable functionality adapted from OpenZeppelin ***/
/// @dev Modifier to allow actions only when the contract IS NOT paused
modifier whenNotPaused() {
require(!paused);
_;
}
/// @dev Modifier to allow actions only when the contract IS paused
modifier whenPaused {
require(paused);
_;
}
/// @dev Called by any "C-level" role to pause the contract. Used only when
/// a bug or exploit is detected and we need to limit damage.
function pause() external onlyCLevel whenNotPaused {
paused = true;
}
/// @dev Unpauses the smart contract. Can only be called by the CEO, since
/// one reason we may pause the contract is when CFO or COO accounts are
/// compromised.
/// @notice This is public rather than external so it can be called by
/// derived contracts.
function unpause() public onlyCEO whenPaused {
// can't unpause if contract was upgraded
paused = false;
}
}
KittyAccessControl Contract では、名前の通り、CryptoKittiesに対するアクセス権限が設定されています。CryptoKittiesには、一般ユーザー以外に特別な3つのroleが存在します。
- CEO → KittyCoreをデプロイするアカウント。他の役割を変更したり、contract をunpause させる権限をもつ唯一のrole.
- CFO → auction Contract から、ETHを引き出すことができるrole.
- COO → gen0猫をリリースする役割と、promoキャットを生成する役割を持つ
この3者の役割は被ることなく別れている。
解説
*modifierというのは関数に何らかの条件を付与する接頭辞
modifier only CEO → CEOのみが行える関数につける修飾子
modifier only CFO → CFOのみが行える関数につける修飾子
modifier only COO → COOのみが行える関数につける修飾子
modifier only CLevel → CEO, CFO ,COO が行える処理
modifier whenNotPaused → paused == false の時
modifier whenPaused → paused == true の時
setCEO → CEOを設定する関数
setCFO → CFOを設定する関数
setCOO → COOを設定する関数
pause → pause = trueにする関数
unpause → pause = falseにする関数
KittyBase
contract KittyBase is KittyAccessControl {
/*** EVENTS ***/
/// @dev The Birth event is fired whenever a new kitten comes into existence. This obviously
/// includes any time a cat is created through the giveBirth method, but it is also called
/// when a new gen0 cat is created.
event Birth(address owner, uint256 kittyId, uint256 matronId, uint256 sireId, uint256 genes);
/// @dev Transfer event as defined in current draft of ERC721. Emitted every time a kitten
/// ownership is assigned, including births.
event Transfer(address from, address to, uint256 tokenId);
/*** DATA TYPES ***/
/// @dev The main Kitty struct. Every cat in CryptoKitties is represented by a copy
/// of this structure, so great care was taken to ensure that it fits neatly into
/// exactly two 256-bit words. Note that the order of the members in this structure
/// is important because of the byte-packing rules used by Ethereum.
/// Ref: http://solidity.readthedocs.io/en/develop/miscellaneous.html
struct Kitty {
// The Kitty's genetic code is packed into these 256-bits, the format is
// sooper-sekret! A cat's genes never change.
uint256 genes;
// The timestamp from the block when this cat came into existence.
uint64 birthTime;
// The minimum timestamp after which this cat can engage in breeding
// activities again. This same timestamp is used for the pregnancy
// timer (for matrons) as well as the siring cooldown.
uint64 cooldownEndBlock;
// The ID of the parents of this kitty, set to 0 for gen0 cats.
// Note that using 32-bit unsigned integers limits us to a "mere"
// 4 billion cats. This number might seem small until you realize
// that Ethereum currently has a limit of about 500 million
// transactions per year! So, this definitely won't be a problem
// for several years (even as Ethereum learns to scale).
uint32 matronId;
uint32 sireId;
// Set to the ID of the sire cat for matrons that are pregnant,
// zero otherwise. A non-zero value here is how we know a cat
// is pregnant. Used to retrieve the genetic material for the new
// kitten when the birth transpires.
uint32 siringWithId;
// Set to the index in the cooldown array (see below) that represents
// the current cooldown duration for this Kitty. This starts at zero
// for gen0 cats, and is initialized to floor(generation/2) for others.
// Incremented by one for each successful breeding action, regardless
// of whether this cat is acting as matron or sire.
uint16 cooldownIndex;
// The "generation number" of this cat. Cats minted by the CK contract
// for sale are called "gen0" and have a generation number of 0. The
// generation number of all other cats is the larger of the two generation
// numbers of their parents, plus one.
// (i.e. max(matron.generation, sire.generation) + 1)
uint16 generation;
}
/*** CONSTANTS ***/
/// @dev A lookup table indicating the cooldown duration after any successful
/// breeding action, called "pregnancy time" for matrons and "siring cooldown"
/// for sires. Designed such that the cooldown roughly doubles each time a cat
/// is bred, encouraging owners not to just keep breeding the same cat over
/// and over again. Caps out at one week (a cat can breed an unbounded number
/// of times, and the maximum cooldown is always seven days).
uint32[14] public cooldowns = [
uint32(1 minutes),
uint32(2 minutes),
uint32(5 minutes),
uint32(10 minutes),
uint32(30 minutes),
uint32(1 hours),
uint32(2 hours),
uint32(4 hours),
uint32(8 hours),
uint32(16 hours),
uint32(1 days),
uint32(2 days),
uint32(4 days),
uint32(7 days)
];
// An approximation of currently how many seconds are in between blocks.
uint256 public secondsPerBlock = 15;
/*** STORAGE ***/
/// @dev An array containing the Kitty struct for all Kitties in existence. The ID
/// of each cat is actually an index into this array. Note that ID 0 is a negacat,
/// the unKitty, the mythical beast that is the parent of all gen0 cats. A bizarre
/// creature that is both matron and sire... to itself! Has an invalid genetic code.
/// In other words, cat ID 0 is invalid... ;-)
Kitty[] kitties;
/// @dev A mapping from cat IDs to the address that owns them. All cats have
/// some valid owner address, even gen0 cats are created with a non-zero owner.
mapping (uint256 => address) public kittyIndexToOwner;
// @dev A mapping from owner address to count of tokens that address owns.
// Used internally inside balanceOf() to resolve ownership count.
mapping (address => uint256) ownershipTokenCount;
/// @dev A mapping from KittyIDs to an address that has been approved to call
/// transferFrom(). Each Kitty can only have one approved address for transfer
/// at any time. A zero value means no approval is outstanding.
mapping (uint256 => address) public kittyIndexToApproved;
/// @dev A mapping from KittyIDs to an address that has been approved to use
/// this Kitty for siring via breedWith(). Each Kitty can only have one approved
/// address for siring at any time. A zero value means no approval is outstanding.
mapping (uint256 => address) public sireAllowedToAddress;
/// @dev The address of the ClockAuction contract that handles sales of Kitties. This
/// same contract handles both peer-to-peer sales as well as the gen0 sales which are
/// initiated every 15 minutes.
SaleClockAuction public saleAuction;
/// @dev The address of a custom ClockAuction subclassed contract that handles siring
/// auctions. Needs to be separate from saleAuction because the actions taken on success
/// after a sales and siring auction are quite different.
SiringClockAuction public siringAuction;
/// @dev Assigns ownership of a specific Kitty to an address.
function _transfer(address _from, address _to, uint256 _tokenId) internal {
// Since the number of kittens is capped to 2^32 we can't overflow this
ownershipTokenCount[_to]++;
// transfer ownership
kittyIndexToOwner[_tokenId] = _to;
// When creating new kittens _from is 0x0, but we can't account that address.
if (_from != address(0)) {
ownershipTokenCount[_from]--;
// once the kitten is transferred also clear sire allowances
delete sireAllowedToAddress[_tokenId];
// clear any previously approved ownership exchange
delete kittyIndexToApproved[_tokenId];
}
// Emit the transfer event.
Transfer(_from, _to, _tokenId);
}
/// @dev An internal method that creates a new kitty and stores it. This
/// method doesn't do any checking and should only be called when the
/// input data is known to be valid. Will generate both a Birth event
/// and a Transfer event.
/// @param _matronId The kitty ID of the matron of this cat (zero for gen0)
/// @param _sireId The kitty ID of the sire of this cat (zero for gen0)
/// @param _generation The generation number of this cat, must be computed by caller.
/// @param _genes The kitty's genetic code.
/// @param _owner The inital owner of this cat, must be non-zero (except for the unKitty, ID 0)
function _createKitty(
uint256 _matronId,
uint256 _sireId,
uint256 _generation,
uint256 _genes,
address _owner
)
internal
returns (uint)
{
// These requires are not strictly necessary, our calling code should make
// sure that these conditions are never broken. However! _createKitty() is already
// an expensive call (for storage), and it doesn't hurt to be especially careful
// to ensure our data structures are always valid.
require(_matronId == uint256(uint32(_matronId)));
require(_sireId == uint256(uint32(_sireId)));
require(_generation == uint256(uint16(_generation)));
// New kitty starts with the same cooldown as parent gen/2
uint16 cooldownIndex = uint16(_generation / 2);
if (cooldownIndex > 13) {
cooldownIndex = 13;
}
Kitty memory _kitty = Kitty({
genes: _genes,
birthTime: uint64(now),
cooldownEndBlock: 0,
matronId: uint32(_matronId),
sireId: uint32(_sireId),
siringWithId: 0,
cooldownIndex: cooldownIndex,
generation: uint16(_generation)
});
uint256 newKittenId = kitties.push(_kitty) - 1;
// It's probably never going to happen, 4 billion cats is A LOT, but
// let's just be 100% sure we never let this happen.
require(newKittenId == uint256(uint32(newKittenId)));
// emit the birth event
Birth(
_owner,
newKittenId,
uint256(_kitty.matronId),
uint256(_kitty.sireId),
_kitty.genes
);
// This will assign ownership, and also emit the Transfer event as
// per ERC721 draft
_transfer(0, _owner, newKittenId);
return newKittenId;
}
// Any C-level can fix how many seconds per blocks are currently observed.
function setSecondsPerBlock(uint256 secs) external onlyCLevel {
require(secs < cooldowns[0]);
secondsPerBlock = secs;
}
}
解説
struct kitty → 猫の持つ要素を並べたもの。
genes → 遺伝子情報 256桁の数字
birthTime → 猫が生成されたブロックのタイムスタンプ
cooldownEndBlock → 猫が再び交配できるようになるまでの最小タイムスタンプ
matronId → 母親猫のtokenId
sireId → 種付猫のtokenId
siringWithId → 妊娠した場合に、相手のsireIdを記録する。妊娠していない場合は0
cooldownIndex → cooldownarrayのindexを保持
generation → 猫の番号 gen0猫は0
cooldowns → 猫の交配に成功した後に、あとどのくらいで次の交配ができるかを示す。
secondsPerBlock → 1ブロックの生成にかかる大体の時間
ownershipTokensCount → 持っているトークンの数
sireAllowedToAddress → 交配が許されたKittyの数
saleAuction → clockAuction コントラクトのアドレス
siringAuction → 後輩のオークションを管理するコントラクト
_transfer → tokenの所有権を移動する関数
_createKitty → 新しい猫を登録する
setSecondsPerBlock → 1ブロックの生成時間を修正する。アップデートとか、トランザクションとかで変化するので結構重要ですね。
KittyOwnership
contract KittyOwnership is KittyBase, ERC721 {
/// @notice Name and symbol of the non fungible token, as defined in ERC721.
string public constant name = "CryptoKitties";
string public constant symbol = "CK";
// The contract that will return kitty metadata
ERC721Metadata public erc721Metadata;
bytes4 constant InterfaceSignature_ERC165 =
bytes4(keccak256('supportsInterface(bytes4)'));
bytes4 constant InterfaceSignature_ERC721 =
bytes4(keccak256('name()')) ^
bytes4(keccak256('symbol()')) ^
bytes4(keccak256('totalSupply()')) ^
bytes4(keccak256('balanceOf(address)')) ^
bytes4(keccak256('ownerOf(uint256)')) ^
bytes4(keccak256('approve(address,uint256)')) ^
bytes4(keccak256('transfer(address,uint256)')) ^
bytes4(keccak256('transferFrom(address,address,uint256)')) ^
bytes4(keccak256('tokensOfOwner(address)')) ^
bytes4(keccak256('tokenMetadata(uint256,string)'));
/// @notice Introspection interface as per ERC-165 (https://github.com/ethereum/EIPs/issues/165).
/// Returns true for any standardized interfaces implemented by this contract. We implement
/// ERC-165 (obviously!) and ERC-721.
function supportsInterface(bytes4 _interfaceID) external view returns (bool)
{
// DEBUG ONLY
//require((InterfaceSignature_ERC165 == 0x01ffc9a7) && (InterfaceSignature_ERC721 == 0x9a20483d));
return ((_interfaceID == InterfaceSignature_ERC165) || (_interfaceID == InterfaceSignature_ERC721));
}
/// @dev Set the address of the sibling contract that tracks metadata.
/// CEO only.
function setMetadataAddress(address _contractAddress) public onlyCEO {
erc721Metadata = ERC721Metadata(_contractAddress);
}
// Internal utility functions: These functions all assume that their input arguments
// are valid. We leave it to public methods to sanitize their inputs and follow
// the required logic.
/// @dev Checks if a given address is the current owner of a particular Kitty.
/// @param _claimant the address we are validating against.
/// @param _tokenId kitten id, only valid when > 0
function _owns(address _claimant, uint256 _tokenId) internal view returns (bool) {
return kittyIndexToOwner[_tokenId] == _claimant;
}
/// @dev Checks if a given address currently has transferApproval for a particular Kitty.
/// @param _claimant the address we are confirming kitten is approved for.
/// @param _tokenId kitten id, only valid when > 0
function _approvedFor(address _claimant, uint256 _tokenId) internal view returns (bool) {
return kittyIndexToApproved[_tokenId] == _claimant;
}
/// @dev Marks an address as being approved for transferFrom(), overwriting any previous
/// approval. Setting _approved to address(0) clears all transfer approval.
/// NOTE: _approve() does NOT send the Approval event. This is intentional because
/// _approve() and transferFrom() are used together for putting Kitties on auction, and
/// there is no value in spamming the log with Approval events in that case.
function _approve(uint256 _tokenId, address _approved) internal {
kittyIndexToApproved[_tokenId] = _approved;
}
/// @notice Returns the number of Kitties owned by a specific address.
/// @param _owner The owner address to check.
/// @dev Required for ERC-721 compliance
function balanceOf(address _owner) public view returns (uint256 count) {
return ownershipTokenCount[_owner];
}
/// @notice Transfers a Kitty to another address. If transferring to a smart
/// contract be VERY CAREFUL to ensure that it is aware of ERC-721 (or
/// CryptoKitties specifically) or your Kitty may be lost forever. Seriously.
/// @param _to The address of the recipient, can be a user or contract.
/// @param _tokenId The ID of the Kitty to transfer.
/// @dev Required for ERC-721 compliance.
function transfer(
address _to,
uint256 _tokenId
)
external
whenNotPaused
{
// Safety check to prevent against an unexpected 0x0 default.
require(_to != address(0));
// Disallow transfers to this contract to prevent accidental misuse.
// The contract should never own any kitties (except very briefly
// after a gen0 cat is created and before it goes on auction).
require(_to != address(this));
// Disallow transfers to the auction contracts to prevent accidental
// misuse. Auction contracts should only take ownership of kitties
// through the allow + transferFrom flow.
require(_to != address(saleAuction));
require(_to != address(siringAuction));
// You can only send your own cat.
require(_owns(msg.sender, _tokenId));
// Reassign ownership, clear pending approvals, emit Transfer event.
_transfer(msg.sender, _to, _tokenId);
}
/// @notice Grant another address the right to transfer a specific Kitty via
/// transferFrom(). This is the preferred flow for transfering NFTs to contracts.
/// @param _to The address to be granted transfer approval. Pass address(0) to
/// clear all approvals.
/// @param _tokenId The ID of the Kitty that can be transferred if this call succeeds.
/// @dev Required for ERC-721 compliance.
function approve(
address _to,
uint256 _tokenId
)
external
whenNotPaused
{
// Only an owner can grant transfer approval.
require(_owns(msg.sender, _tokenId));
// Register the approval (replacing any previous approval).
_approve(_tokenId, _to);
// Emit approval event.
Approval(msg.sender, _to, _tokenId);
}
/// @notice Transfer a Kitty owned by another address, for which the calling address
/// has previously been granted transfer approval by the owner.
/// @param _from The address that owns the Kitty to be transfered.
/// @param _to The address that should take ownership of the Kitty. Can be any address,
/// including the caller.
/// @param _tokenId The ID of the Kitty to be transferred.
/// @dev Required for ERC-721 compliance.
function transferFrom(
address _from,
address _to,
uint256 _tokenId
)
external
whenNotPaused
{
// Safety check to prevent against an unexpected 0x0 default.
require(_to != address(0));
// Disallow transfers to this contract to prevent accidental misuse.
// The contract should never own any kitties (except very briefly
// after a gen0 cat is created and before it goes on auction).
require(_to != address(this));
// Check for approval and valid ownership
require(_approvedFor(msg.sender, _tokenId));
require(_owns(_from, _tokenId));
// Reassign ownership (also clears pending approvals and emits Transfer event).
_transfer(_from, _to, _tokenId);
}
/// @notice Returns the total number of Kitties currently in existence.
/// @dev Required for ERC-721 compliance.
function totalSupply() public view returns (uint) {
return kitties.length - 1;
}
/// @notice Returns the address currently assigned ownership of a given Kitty.
/// @dev Required for ERC-721 compliance.
function ownerOf(uint256 _tokenId)
external
view
returns (address owner)
{
owner = kittyIndexToOwner[_tokenId];
require(owner != address(0));
}
/// @notice Returns a list of all Kitty IDs assigned to an address.
/// @param _owner The owner whose Kitties we are interested in.
/// @dev This method MUST NEVER be called by smart contract code. First, it's fairly
/// expensive (it walks the entire Kitty array looking for cats belonging to owner),
/// but it also returns a dynamic array, which is only supported for web3 calls, and
/// not contract-to-contract calls.
function tokensOfOwner(address _owner) external view returns(uint256[] ownerTokens) {
uint256 tokenCount = balanceOf(_owner);
if (tokenCount == 0) {
// Return an empty array
return new uint256[](0);
} else {
uint256[] memory result = new uint256[](tokenCount);
uint256 totalCats = totalSupply();
uint256 resultIndex = 0;
// We count on the fact that all cats have IDs starting at 1 and increasing
// sequentially up to the totalCat count.
uint256 catId;
for (catId = 1; catId <= totalCats; catId++) {
if (kittyIndexToOwner[catId] == _owner) {
result[resultIndex] = catId;
resultIndex++;
}
}
return result;
}
}
/// @dev Adapted from memcpy() by @arachnid (Nick Johnson <arachnid@notdot.net>)
/// This method is licenced under the Apache License.
/// Ref: https://github.com/Arachnid/solidity-stringutils/blob/2f6ca9accb48ae14c66f1437ec50ed19a0616f78/strings.sol
function _memcpy(uint _dest, uint _src, uint _len) private view {
// Copy word-length chunks while possible
for(; _len >= 32; _len -= 32) {
assembly {
mstore(_dest, mload(_src))
}
_dest += 32;
_src += 32;
}
// Copy remaining bytes
uint256 mask = 256 ** (32 - _len) - 1;
assembly {
let srcpart := and(mload(_src), not(mask))
let destpart := and(mload(_dest), mask)
mstore(_dest, or(destpart, srcpart))
}
}
/// @dev Adapted from toString(slice) by @arachnid (Nick Johnson <arachnid@notdot.net>)
/// This method is licenced under the Apache License.
/// Ref: https://github.com/Arachnid/solidity-stringutils/blob/2f6ca9accb48ae14c66f1437ec50ed19a0616f78/strings.sol
function _toString(bytes32[4] _rawBytes, uint256 _stringLength) private view returns (string) {
var outputString = new string(_stringLength);
uint256 outputPtr;
uint256 bytesPtr;
assembly {
outputPtr := add(outputString, 32)
bytesPtr := _rawBytes
}
_memcpy(outputPtr, bytesPtr, _stringLength);
return outputString;
}
/// @notice Returns a URI pointing to a metadata package for this token conforming to
/// ERC-721 (https://github.com/ethereum/EIPs/issues/721)
/// @param _tokenId The ID number of the Kitty whose metadata should be returned.
function tokenMetadata(uint256 _tokenId, string _preferredTransport) external view returns (string infoUrl) {
require(erc721Metadata != address(0));
bytes32[4] memory buffer;
uint256 count;
(buffer, count) = erc721Metadata.getMetadata(_tokenId, _preferredTransport);
return _toString(buffer, count);
}
}
InterfaceSignature_ERC165 、 InterfaceSignature_ERC721 → ERC165とERC721のInterfaceのsha3hash 化したInterfaceです。
supportsInterface → ERC165 と ERC721 の Interfaceと一致するか確認
erc721Metadata → 猫のメタデータのコントラクトのaddress
setMetadataAddress → メタデータをセットするコントラクトのアドレスを変更
_owns → 引数のトークンの猫がそのaddress の持ち主かどうかを確認
_approvedFor → 猫の所有権をもらう権利があるかどうかを確認
_approve → 猫の所有権をもらう権利を付与 (internal関数だからcontractの中からのみ呼べる)
transfer → 猫の所有権を移す。内部はバリデーション+ _transfer
approve → 猫の所有権を移す権利を与える。バリデーション+ _approve
transferFrom → approveされている猫の権利を自分に移す。
totalSupply → 猫の数を返す
ownerOf → 持ち主のaddressを返す
tokensOfOwner → ownerが持っている猫のid一覧を返す
_memcpy, toString ,は
ここの中からtoStringのみ実装したものですね。solidityにはもともとstring ようにsplit や toStringとかのメソッドが用意されていないので、assemblyを利用して自分で実装する必要があるみたいです。
KittyBreeding
contract KittyBreeding is KittyOwnership {
/// @dev The Pregnant event is fired when two cats successfully breed and the pregnancy
/// timer begins for the matron.
event Pregnant(address owner, uint256 matronId, uint256 sireId, uint256 cooldownEndBlock);
/// @notice The minimum payment required to use breedWithAuto(). This fee goes towards
/// the gas cost paid by whatever calls giveBirth(), and can be dynamically updated by
/// the COO role as the gas price changes.
uint256 public autoBirthFee = 2 finney;
// Keeps track of number of pregnant kitties.
uint256 public pregnantKitties;
/// @dev The address of the sibling contract that is used to implement the sooper-sekret
/// genetic combination algorithm.
GeneScienceInterface public geneScience;
/// @dev Update the address of the genetic contract, can only be called by the CEO.
/// @param _address An address of a GeneScience contract instance to be used from this point forward.
function setGeneScienceAddress(address _address) external onlyCEO {
GeneScienceInterface candidateContract = GeneScienceInterface(_address);
// NOTE: verify that a contract is what we expect - https://github.com/Lunyr/crowdsale-contracts/blob/cfadd15986c30521d8ba7d5b6f57b4fefcc7ac38/contracts/LunyrToken.sol#L117
require(candidateContract.isGeneScience());
// Set the new contract address
geneScience = candidateContract;
}
/// @dev Checks that a given kitten is able to breed. Requires that the
/// current cooldown is finished (for sires) and also checks that there is
/// no pending pregnancy.
function _isReadyToBreed(Kitty _kit) internal view returns (bool) {
// In addition to checking the cooldownEndBlock, we also need to check to see if
// the cat has a pending birth; there can be some period of time between the end
// of the pregnacy timer and the birth event.
return (_kit.siringWithId == 0) && (_kit.cooldownEndBlock <= uint64(block.number));
}
/// @dev Check if a sire has authorized breeding with this matron. True if both sire
/// and matron have the same owner, or if the sire has given siring permission to
/// the matron's owner (via approveSiring()).
function _isSiringPermitted(uint256 _sireId, uint256 _matronId) internal view returns (bool) {
address matronOwner = kittyIndexToOwner[_matronId];
address sireOwner = kittyIndexToOwner[_sireId];
// Siring is okay if they have same owner, or if the matron's owner was given
// permission to breed with this sire.
return (matronOwner == sireOwner || sireAllowedToAddress[_sireId] == matronOwner);
}
/// @dev Set the cooldownEndTime for the given Kitty, based on its current cooldownIndex.
/// Also increments the cooldownIndex (unless it has hit the cap).
/// @param _kitten A reference to the Kitty in storage which needs its timer started.
function _triggerCooldown(Kitty storage _kitten) internal {
// Compute an estimation of the cooldown time in blocks (based on current cooldownIndex).
_kitten.cooldownEndBlock = uint64((cooldowns[_kitten.cooldownIndex]/secondsPerBlock) + block.number);
// Increment the breeding count, clamping it at 13, which is the length of the
// cooldowns array. We could check the array size dynamically, but hard-coding
// this as a constant saves gas. Yay, Solidity!
if (_kitten.cooldownIndex < 13) {
_kitten.cooldownIndex += 1;
}
}
/// @notice Grants approval to another user to sire with one of your Kitties.
/// @param _addr The address that will be able to sire with your Kitty. Set to
/// address(0) to clear all siring approvals for this Kitty.
/// @param _sireId A Kitty that you own that _addr will now be able to sire with.
function approveSiring(address _addr, uint256 _sireId)
external
whenNotPaused
{
require(_owns(msg.sender, _sireId));
sireAllowedToAddress[_sireId] = _addr;
}
/// @dev Updates the minimum payment required for calling giveBirthAuto(). Can only
/// be called by the COO address. (This fee is used to offset the gas cost incurred
/// by the autobirth daemon).
function setAutoBirthFee(uint256 val) external onlyCOO {
autoBirthFee = val;
}
/// @dev Checks to see if a given Kitty is pregnant and (if so) if the gestation
/// period has passed.
function _isReadyToGiveBirth(Kitty _matron) private view returns (bool) {
return (_matron.siringWithId != 0) && (_matron.cooldownEndBlock <= uint64(block.number));
}
/// @notice Checks that a given kitten is able to breed (i.e. it is not pregnant or
/// in the middle of a siring cooldown).
/// @param _kittyId reference the id of the kitten, any user can inquire about it
function isReadyToBreed(uint256 _kittyId)
public
view
returns (bool)
{
require(_kittyId > 0);
Kitty storage kit = kitties[_kittyId];
return _isReadyToBreed(kit);
}
/// @dev Checks whether a kitty is currently pregnant.
/// @param _kittyId reference the id of the kitten, any user can inquire about it
function isPregnant(uint256 _kittyId)
public
view
returns (bool)
{
require(_kittyId > 0);
// A kitty is pregnant if and only if this field is set
return kitties[_kittyId].siringWithId != 0;
}
/// @dev Internal check to see if a given sire and matron are a valid mating pair. DOES NOT
/// check ownership permissions (that is up to the caller).
/// @param _matron A reference to the Kitty struct of the potential matron.
/// @param _matronId The matron's ID.
/// @param _sire A reference to the Kitty struct of the potential sire.
/// @param _sireId The sire's ID
function _isValidMatingPair(
Kitty storage _matron,
uint256 _matronId,
Kitty storage _sire,
uint256 _sireId
)
private
view
returns(bool)
{
// A Kitty can't breed with itself!
if (_matronId == _sireId) {
return false;
}
// Kitties can't breed with their parents.
if (_matron.matronId == _sireId || _matron.sireId == _sireId) {
return false;
}
if (_sire.matronId == _matronId || _sire.sireId == _matronId) {
return false;
}
// We can short circuit the sibling check (below) if either cat is
// gen zero (has a matron ID of zero).
if (_sire.matronId == 0 || _matron.matronId == 0) {
return true;
}
// Kitties can't breed with full or half siblings.
if (_sire.matronId == _matron.matronId || _sire.matronId == _matron.sireId) {
return false;
}
if (_sire.sireId == _matron.matronId || _sire.sireId == _matron.sireId) {
return false;
}
// Everything seems cool! Let's get DTF.
return true;
}
/// @dev Internal check to see if a given sire and matron are a valid mating pair for
/// breeding via auction (i.e. skips ownership and siring approval checks).
function _canBreedWithViaAuction(uint256 _matronId, uint256 _sireId)
internal
view
returns (bool)
{
Kitty storage matron = kitties[_matronId];
Kitty storage sire = kitties[_sireId];
return _isValidMatingPair(matron, _matronId, sire, _sireId);
}
/// @notice Checks to see if two cats can breed together, including checks for
/// ownership and siring approvals. Does NOT check that both cats are ready for
/// breeding (i.e. breedWith could still fail until the cooldowns are finished).
/// TODO: Shouldn't this check pregnancy and cooldowns?!?
/// @param _matronId The ID of the proposed matron.
/// @param _sireId The ID of the proposed sire.
function canBreedWith(uint256 _matronId, uint256 _sireId)
external
view
returns(bool)
{
require(_matronId > 0);
require(_sireId > 0);
Kitty storage matron = kitties[_matronId];
Kitty storage sire = kitties[_sireId];
return _isValidMatingPair(matron, _matronId, sire, _sireId) &&
_isSiringPermitted(_sireId, _matronId);
}
/// @dev Internal utility function to initiate breeding, assumes that all breeding
/// requirements have been checked.
function _breedWith(uint256 _matronId, uint256 _sireId) internal {
// Grab a reference to the Kitties from storage.
Kitty storage sire = kitties[_sireId];
Kitty storage matron = kitties[_matronId];
// Mark the matron as pregnant, keeping track of who the sire is.
matron.siringWithId = uint32(_sireId);
// Trigger the cooldown for both parents.
_triggerCooldown(sire);
_triggerCooldown(matron);
// Clear siring permission for both parents. This may not be strictly necessary
// but it's likely to avoid confusion!
delete sireAllowedToAddress[_matronId];
delete sireAllowedToAddress[_sireId];
// Every time a kitty gets pregnant, counter is incremented.
pregnantKitties++;
// Emit the pregnancy event.
Pregnant(kittyIndexToOwner[_matronId], _matronId, _sireId, matron.cooldownEndBlock);
}
/// @notice Breed a Kitty you own (as matron) with a sire that you own, or for which you
/// have previously been given Siring approval. Will either make your cat pregnant, or will
/// fail entirely. Requires a pre-payment of the fee given out to the first caller of giveBirth()
/// @param _matronId The ID of the Kitty acting as matron (will end up pregnant if successful)
/// @param _sireId The ID of the Kitty acting as sire (will begin its siring cooldown if successful)
function breedWithAuto(uint256 _matronId, uint256 _sireId)
external
payable
whenNotPaused
{
// Checks for payment.
require(msg.value >= autoBirthFee);
// Caller must own the matron.
require(_owns(msg.sender, _matronId));
// Neither sire nor matron are allowed to be on auction during a normal
// breeding operation, but we don't need to check that explicitly.
// For matron: The caller of this function can't be the owner of the matron
// because the owner of a Kitty on auction is the auction house, and the
// auction house will never call breedWith().
// For sire: Similarly, a sire on auction will be owned by the auction house
// and the act of transferring ownership will have cleared any oustanding
// siring approval.
// Thus we don't need to spend gas explicitly checking to see if either cat
// is on auction.
// Check that matron and sire are both owned by caller, or that the sire
// has given siring permission to caller (i.e. matron's owner).
// Will fail for _sireId = 0
require(_isSiringPermitted(_sireId, _matronId));
// Grab a reference to the potential matron
Kitty storage matron = kitties[_matronId];
// Make sure matron isn't pregnant, or in the middle of a siring cooldown
require(_isReadyToBreed(matron));
// Grab a reference to the potential sire
Kitty storage sire = kitties[_sireId];
// Make sure sire isn't pregnant, or in the middle of a siring cooldown
require(_isReadyToBreed(sire));
// Test that these cats are a valid mating pair.
require(_isValidMatingPair(
matron,
_matronId,
sire,
_sireId
));
// All checks passed, kitty gets pregnant!
_breedWith(_matronId, _sireId);
}
/// @notice Have a pregnant Kitty give birth!
/// @param _matronId A Kitty ready to give birth.
/// @return The Kitty ID of the new kitten.
/// @dev Looks at a given Kitty and, if pregnant and if the gestation period has passed,
/// combines the genes of the two parents to create a new kitten. The new Kitty is assigned
/// to the current owner of the matron. Upon successful completion, both the matron and the
/// new kitten will be ready to breed again. Note that anyone can call this function (if they
/// are willing to pay the gas!), but the new kitten always goes to the mother's owner.
function giveBirth(uint256 _matronId)
external
whenNotPaused
returns(uint256)
{
// Grab a reference to the matron in storage.
Kitty storage matron = kitties[_matronId];
// Check that the matron is a valid cat.
require(matron.birthTime != 0);
// Check that the matron is pregnant, and that its time has come!
require(_isReadyToGiveBirth(matron));
// Grab a reference to the sire in storage.
uint256 sireId = matron.siringWithId;
Kitty storage sire = kitties[sireId];
// Determine the higher generation number of the two parents
uint16 parentGen = matron.generation;
if (sire.generation > matron.generation) {
parentGen = sire.generation;
}
// Call the sooper-sekret gene mixing operation.
uint256 childGenes = geneScience.mixGenes(matron.genes, sire.genes, matron.cooldownEndBlock - 1);
// Make the new kitten!
address owner = kittyIndexToOwner[_matronId];
uint256 kittenId = _createKitty(_matronId, matron.siringWithId, parentGen + 1, childGenes, owner);
// Clear the reference to sire from the matron (REQUIRED! Having siringWithId
// set is what marks a matron as being pregnant.)
delete matron.siringWithId;
// Every time a kitty gives birth counter is decremented.
pregnantKitties--;
// Send the balance fee to the person who made birth happen.
msg.sender.send(autoBirthFee);
// return the new kitten's ID
return kittenId;
}
}
状態変数
autoBirthFee → 猫を産む時に最低限かかる手数料
pregnantKitties → 妊娠中の猫の数を保持する
geneScience → 親の遺伝情報を元に子供の遺伝情報を生成するコントラクト
関数
setGeneScienceAddress → geneScienceの元になるコントラクトを指定する
_isReadyToBreed → 猫が現在妊娠可能かどうか調べる
_isSiringPermitted → 交配可能な猫かどうかを調べる
_triggerCooldown → cooldownをスタートさせる。
approveSiring → 交配する許可を与える。
setAutoBirthFee → autoBirthFeeを設定する
_isReadyToGiveBirth → 子供をうむことができる状態にあるかを確認
isReadyToBreed → バリデーション ＋ _isReadyToBreed
isPregnant → 現在妊娠しているかどうか
_isValidMatingPair → 自分自身や両親とは交配できないように設定。
_canBreedWithViaAuction → _isValidMatingPair を実行してるだけ。
canBreedWith → _isValidMatingPair ＆＆ _isSiringPermitted
_breedWith → siringWithId を設定、pregnantKittiesに+1、 sireAllowedToAddressの削除をする。妊娠の設定。
breedWithAuto → バリデーション+ _breedWith
giveBirth → 新たに猫を追加。妊娠に関する情報を削除。
KittyAuction
contract KittyAuction is KittyBreeding {
// @notice The auction contract variables are defined in KittyBase to allow
// us to refer to them in KittyOwnership to prevent accidental transfers.
// `saleAuction` refers to the auction for gen0 and p2p sale of kitties.
// `siringAuction` refers to the auction for siring rights of kitties.
/// @dev Sets the reference to the sale auction.
/// @param _address - Address of sale contract.
function setSaleAuctionAddress(address _address) external onlyCEO {
SaleClockAuction candidateContract = SaleClockAuction(_address);
// NOTE: verify that a contract is what we expect - https://github.com/Lunyr/crowdsale-contracts/blob/cfadd15986c30521d8ba7d5b6f57b4fefcc7ac38/contracts/LunyrToken.sol#L117
require(candidateContract.isSaleClockAuction());
// Set the new contract address
saleAuction = candidateContract;
}
/// @dev Sets the reference to the siring auction.
/// @param _address - Address of siring contract.
function setSiringAuctionAddress(address _address) external onlyCEO {
SiringClockAuction candidateContract = SiringClockAuction(_address);
// NOTE: verify that a contract is what we expect - https://github.com/Lunyr/crowdsale-contracts/blob/cfadd15986c30521d8ba7d5b6f57b4fefcc7ac38/contracts/LunyrToken.sol#L117
require(candidateContract.isSiringClockAuction());
// Set the new contract address
siringAuction = candidateContract;
}
/// @dev Put a kitty up for auction.
/// Does some ownership trickery to create auctions in one tx.
function createSaleAuction(
uint256 _kittyId,
uint256 _startingPrice,
uint256 _endingPrice,
uint256 _duration
)
external
whenNotPaused
{
// Auction contract checks input sizes
// If kitty is already on any auction, this will throw
// because it will be owned by the auction contract.
require(_owns(msg.sender, _kittyId));
// Ensure the kitty is not pregnant to prevent the auction
// contract accidentally receiving ownership of the child.
// NOTE: the kitty IS allowed to be in a cooldown.
require(!isPregnant(_kittyId));
_approve(_kittyId, saleAuction);
// Sale auction throws if inputs are invalid and clears
// transfer and sire approval after escrowing the kitty.
saleAuction.createAuction(
_kittyId,
_startingPrice,
_endingPrice,
_duration,
msg.sender
);
}
/// @dev Put a kitty up for auction to be sire.
/// Performs checks to ensure the kitty can be sired, then
/// delegates to reverse auction.
function createSiringAuction(
uint256 _kittyId,
uint256 _startingPrice,
uint256 _endingPrice,
uint256 _duration
)
external
whenNotPaused
{
// Auction contract checks input sizes
// If kitty is already on any auction, this will throw
// because it will be owned by the auction contract.
require(_owns(msg.sender, _kittyId));
require(isReadyToBreed(_kittyId));
_approve(_kittyId, siringAuction);
// Siring auction throws if inputs are invalid and clears
// transfer and sire approval after escrowing the kitty.
siringAuction.createAuction(
_kittyId,
_startingPrice,
_endingPrice,
_duration,
msg.sender
);
}
/// @dev Completes a siring auction by bidding.
/// Immediately breeds the winning matron with the sire on auction.
/// @param _sireId - ID of the sire on auction.
/// @param _matronId - ID of the matron owned by the bidder.
function bidOnSiringAuction(
uint256 _sireId,
uint256 _matronId
)
external
payable
whenNotPaused
{
// Auction contract checks input sizes
require(_owns(msg.sender, _matronId));
require(isReadyToBreed(_matronId));
require(_canBreedWithViaAuction(_matronId, _sireId));
// Define the current price of the auction.
uint256 currentPrice = siringAuction.getCurrentPrice(_sireId);
require(msg.value >= currentPrice + autoBirthFee);
// Siring auction will throw if the bid fails.
siringAuction.bid.value(msg.value - autoBirthFee)(_sireId);
_breedWith(uint32(_matronId), uint32(_sireId));
}
/// @dev Transfers the balance of the sale auction contract
/// to the KittyCore contract. We use two-step withdrawal to
/// prevent two transfer calls in the auction bid function.
function withdrawAuctionBalances() external onlyCLevel {
saleAuction.withdrawBalance();
siringAuction.withdrawBalance();
}
}
ちょっといまいち上手くまとまらないのでまとめ方を変えますが、ご容赦ください。
状態変数
なし
event
なし
関数
setSaleAuctionAddress → Auction Contractのアドレスを設定する
createSaleAuction → Auctionの設定をする。始値、終値、開催時間、猫のId
createSiringAuction → 交配のオークションを開催
bidOnSiringAuction → 入札が決まったら交配する
withdrawAuctionBalances → auctionContractに溜まった手数料を引き出す。
KittyMinting
/// @title all functions related to creating kittens
contract KittyMinting is KittyAuction {
// Limits the number of cats the contract owner can ever create.
uint256 public constant PROMO_CREATION_LIMIT = 5000;
uint256 public constant GEN0_CREATION_LIMIT = 45000;
// Constants for gen0 auctions.
uint256 public constant GEN0_STARTING_PRICE = 10 finney;
uint256 public constant GEN0_AUCTION_DURATION = 1 days;
// Counts the number of cats the contract owner has created.
uint256 public promoCreatedCount;
uint256 public gen0CreatedCount;
/// @dev we can create promo kittens, up to a limit. Only callable by COO
/// @param _genes the encoded genes of the kitten to be created, any value is accepted
/// @param _owner the future owner of the created kittens. Default to contract COO
function createPromoKitty(uint256 _genes, address _owner) external onlyCOO {
address kittyOwner = _owner;
if (kittyOwner == address(0)) {
kittyOwner = cooAddress;
}
require(promoCreatedCount < PROMO_CREATION_LIMIT);
promoCreatedCount++;
_createKitty(0, 0, 0, _genes, kittyOwner);
}
/// @dev Creates a new gen0 kitty with the given genes and
/// creates an auction for it.
function createGen0Auction(uint256 _genes) external onlyCOO {
require(gen0CreatedCount < GEN0_CREATION_LIMIT);
uint256 kittyId = _createKitty(0, 0, 0, _genes, address(this));
_approve(kittyId, saleAuction);
saleAuction.createAuction(
kittyId,
_computeNextGen0Price(),
0,
GEN0_AUCTION_DURATION,
address(this)
);
gen0CreatedCount++;
}
/// @dev Computes the next gen0 auction starting price, given
/// the average of the past 5 prices + 50%.
function _computeNextGen0Price() internal view returns (uint256) {
uint256 avePrice = saleAuction.averageGen0SalePrice();
// Sanity check to ensure we don't overflow arithmetic
require(avePrice == uint256(uint128(avePrice)));
uint256 nextPrice = avePrice + (avePrice / 2);
// We never auction for less than starting price
if (nextPrice < GEN0_STARTING_PRICE) {
nextPrice = GEN0_STARTING_PRICE;
}
return nextPrice;
}
}
状態変数
PROMO_CREATION_LIMIT → promo猫の限界数
GEN0_CREATION_LIMIT → gen0の限界数
GEN0_STARTING_PRICE → gen0auctionのスタートプライス
GEN0_AUCTION_DURATION → gen0auctionの期間
promoCreatedCount → 産み出されたpromo猫の数
gen0CreatedCount → 産み出されたgen0猫の数
event
なし
関数
createPromoKitty → promo猫を生成
createGen0Auction → gen0猫のオークションを開催
_computeNextGen0Price → 次のgen0猫のオークションの始値を返す
KittyCore
contract KittyCore is KittyMinting {
// This is the main CryptoKitties contract. In order to keep our code seperated into logical sections,
// we've broken it up in two ways. First, we have several seperately-instantiated sibling contracts
// that handle auctions and our super-top-secret genetic combination algorithm. The auctions are
// seperate since their logic is somewhat complex and there's always a risk of subtle bugs. By keeping
// them in their own contracts, we can upgrade them without disrupting the main contract that tracks
// kitty ownership. The genetic combination algorithm is kept seperate so we can open-source all of
// the rest of our code without making it _too_ easy for folks to figure out how the genetics work.
// Don't worry, I'm sure someone will reverse engineer it soon enough!
//
// Secondly, we break the core contract into multiple files using inheritence, one for each major
// facet of functionality of CK. This allows us to keep related code bundled together while still
// avoiding a single giant file with everything in it. The breakdown is as follows:
//
// - KittyBase: This is where we define the most fundamental code shared throughout the core
// functionality. This includes our main data storage, constants and data types, plus
// internal functions for managing these items.
//
// - KittyAccessControl: This contract manages the various addresses and constraints for operations
// that can be executed only by specific roles. Namely CEO, CFO and COO.
//
// - KittyOwnership: This provides the methods required for basic non-fungible token
// transactions, following the draft ERC-721 spec (https://github.com/ethereum/EIPs/issues/721).
//
// - KittyBreeding: This file contains the methods necessary to breed cats together, including
// keeping track of siring offers, and relies on an external genetic combination contract.
//
// - KittyAuctions: Here we have the public methods for auctioning or bidding on cats or siring
// services. The actual auction functionality is handled in two sibling contracts (one
// for sales and one for siring), while auction creation and bidding is mostly mediated
// through this facet of the core contract.
//
// - KittyMinting: This final facet contains the functionality we use for creating new gen0 cats.
// We can make up to 5000 "promo" cats that can be given away (especially important when
// the community is new), and all others can only be created and then immediately put up
// for auction via an algorithmically determined starting price. Regardless of how they
// are created, there is a hard limit of 50k gen0 cats. After that, it's all up to the
// community to breed, breed, breed!
// Set in case the core contract is broken and an upgrade is required
address public newContractAddress;
/// @notice Creates the main CryptoKitties smart contract instance.
function KittyCore() public {
// Starts paused.
paused = true;
// the creator of the contract is the initial CEO
ceoAddress = msg.sender;
// the creator of the contract is also the initial COO
cooAddress = msg.sender;
// start with the mythical kitten 0 - so we don't have generation-0 parent issues
_createKitty(0, 0, 0, uint256(-1), address(0));
}
/// @dev Used to mark the smart contract as upgraded, in case there is a serious
/// breaking bug. This method does nothing but keep track of the new contract and
/// emit a message indicating that the new address is set. It's up to clients of this
/// contract to update to the new contract address in that case. (This contract will
/// be paused indefinitely if such an upgrade takes place.)
/// @param _v2Address new address
function setNewAddress(address _v2Address) external onlyCEO whenPaused {
// See README.md for updgrade plan
newContractAddress = _v2Address;
ContractUpgrade(_v2Address);
}
/// @notice No tipping!
/// @dev Reject all Ether from being sent here, unless it's from one of the
/// two auction contracts. (Hopefully, we can prevent user accidents.)
function() external payable {
require(
msg.sender == address(saleAuction) ||
msg.sender == address(siringAuction)
);
}
/// @notice Returns all the relevant information about a specific kitty.
/// @param _id The ID of the kitty of interest.
function getKitty(uint256 _id)
external
view
returns (
bool isGestating,
bool isReady,
uint256 cooldownIndex,
uint256 nextActionAt,
uint256 siringWithId,
uint256 birthTime,
uint256 matronId,
uint256 sireId,
uint256 generation,
uint256 genes
) {
Kitty storage kit = kitties[_id];
// if this variable is 0 then it's not gestating
isGestating = (kit.siringWithId != 0);
isReady = (kit.cooldownEndBlock <= block.number);
cooldownIndex = uint256(kit.cooldownIndex);
nextActionAt = uint256(kit.cooldownEndBlock);
siringWithId = uint256(kit.siringWithId);
birthTime = uint256(kit.birthTime);
matronId = uint256(kit.matronId);
sireId = uint256(kit.sireId);
generation = uint256(kit.generation);
genes = kit.genes;
}
/// @dev Override unpause so it requires all external contract addresses
/// to be set before contract can be unpaused. Also, we can't have
/// newContractAddress set either, because then the contract was upgraded.
/// @notice This is public rather than external so we can call super.unpause
/// without using an expensive CALL.
function unpause() public onlyCEO whenPaused {
require(saleAuction != address(0));
require(siringAuction != address(0));
require(geneScience != address(0));
require(newContractAddress == address(0));
// Actually unpause the contract.
super.unpause();
}
// @dev Allows the CFO to capture the balance available to the contract.
function withdrawBalance() external onlyCFO {
uint256 balance = this.balance;
// Subtract all the currently pregnant kittens we have, plus 1 of margin.
uint256 subtractFees = (pregnantKitties + 1) * autoBirthFee;
if (balance > subtractFees) {
cfoAddress.send(balance - subtractFees);
}
}
}
状態変数
newContractAddress → アップデートがあった時にコントラクトを変更するための変数
event
なし
関数
KittyCore → コンストラクタ
setNewAddress → 新しいコントラクトのアドレスを設定する
getKitty → 猫の情報を返す
unpause → コントラクトを動かす
withdrawBalance → コントラクトからETHを引き出す。
なんか、あまりうまいことまとまらなかったですが、とりあえず網羅したということで、投稿しておきます。