Aptos Coin

Aptos Coin #

Coin 为简单的、可替代的代币或硬币提供标准的、类型安全的框架。

Structures #

  • Reusability #

coin 在 Move 中被定义为：

struct Coin<phantom CoinType> has store {
    /// Amount of coin this address has.
    value: u64,
}

Coin 使用 CoinType 来支持不同 Coins 的 Coin 框架的可重用性。例如，Coin<A> 和 Coin<B> 是两个不同的钱币。

  • Global Store #

Coin 还支持在全局商店中存储硬币的资源：

struct CoinStore<phantom CoinType> has key {
    coin: Coin<CoinType>,
    frozen: bool,
    deposit_events: EventHandle<DepositEvent>,
    withdraw_events: EventHandle<WithdrawEvent>,
}

钱币信息或元数据存储在硬币创建者帐户下的全球商店中：

struct CoinInfo<phantom CoinType> has key {
    name: string::String,
    /// Symbol of the coin, usually a shorter version of the name.
    /// For example, Singapore Dollar is SGD.
    symbol: string::String,
    /// Number of decimals used to get its user representation.
    /// For example, if `decimals` equals `2`, a balance of `505` coins should
    /// be displayed to a user as `5.05` (`505 / 10 ** 2`).
    decimals: u8,
    /// Amount of this coin type in existence.
    supply: Option<OptionalAggregator>,
}

Creating a new CoinType #

硬币创建者可以向链上帐户发布一个新模块，该模块定义一个结构来表示新的 CoinType。然后硬币创建者将从该帐户调用 coin:initialize<CoinType> 以将其注册为有效硬币，并作为回报接收回结构，这些结构允许调用函数来销毁和铸造硬币并冻结 CoinStores。这些将需要由创建者存储在全局存储中以管理代币的使用。

public fun initialize<CoinType>(
    account: &signer,
    name: string::String,
    symbol: string::String,
    decimals: u8,
    monitor_supply: bool,
): (BurnCapability<CoinType>, FreezeCapability<CoinType>, MintCapability<CoinType>) {
  • 上面的前三个（名称、符号、小数）是纯元数据，对链上应用程序没有影响。一些应用程序可能使用小数来将单个硬币与分数硬币等同起来。
  • 监控供应 (monitor_supply) 有助于跟踪供应总量。但是，由于并行执行器的工作方式，打开此选项将阻止 mint 和 burn 的任何并行执行。如果硬币将定期铸造或销毁，请考虑禁用 monitor_supply。

Minting Coins #

如果创建者或管理者想要铸造硬币，他们必须检索对在初始化中生成的 MintCapability 的引用，并调用：

public fun mint<CoinType>(
    amount: u64,
    _cap: &MintCapability<CoinType>,
): Coin<CoinType> acquires CoinInfo {

这将产生一个新的 Coin 结构，其中包含一个由金额决定的值。如果跟踪供应，那么它也会进行调整。

Burning Coins​ #

如果创建者或管理者想要销毁代币，他们必须检索在初始化时生成的对其 BurnCapability 的引用，并调用：

If the creator or manager would like to burn coins, they must retrieve a reference to their BurnCapability, which was produced in the initialize, and call:

public fun burn<CoinType>(
    coin: Coin<CoinType>,
    _cap: &BurnCapability<CoinType>,
) acquires CoinInfo {

创建者或管理者也可以从 CoinStore 销毁硬币：

public fun burn_from<CoinType>(
    account_addr: address,
    amount: u64,
    burn_cap: &BurnCapability<CoinType>,
) acquires CoinInfo, CoinStore {

Freezing Accounts​ #

如果创建者或管理者想冻结特定账户上的 CoinStore，他们必须检索对他们在初始化时产生的 FreezeCapability 的引用，并调用：

public entry fun freeze_coin_store<CoinType>(
    account_addr: address,
    _freeze_cap: &FreezeCapability<CoinType>,
) acquires CoinStore {

Merging Coins​ #

两个相同类型的硬币可以合并成一个单独的 Coin 结构，通过调用：

public fun merge<CoinType>(
    dst_coin: &mut Coin<CoinType>,
    source_coin: Coin<CoinType>,
) {

Extracting Coins​ #

可以通过调用以下方式扣除一个硬币的价值以创建另一个硬币：

public fun extract<CoinType>(
        coin: &mut Coin<CoinType>,
        amount: u64,
): Coin<CoinType> {

Withdrawing Coins from CoinStore​ #

CoinStore 的持有者可以通过调用以下方式提取指定价值的 Coin：

public fun withdraw<CoinType>(
    account: &signer,
    amount: u64,
): Coin<CoinType> acquires CoinStore {

Depositing Coins into CoinStore​ #

任何实体都可以通过调用以下方式将硬币存入帐户的 CoinStore：

public fun deposit<CoinType>(
        account_addr: address,
        coin: Coin<CoinType>,
) acquires CoinStore {

Transferring Coins​ #

CoinStore 的持有人可以通过调用以下方式直接将硬币从他们的账户转移到另一个账户的 CoinStore：

public entry fun transfer<CoinType>(
    from: &signer,
    to: address,
    amount: u64,
) acquires CoinStore {

Events​ #

struct DepositEvent has drop, store {
    amount: u64,
}

struct WithdrawEvent has drop, store {
    amount: u64,
}