Trait frame_support::traits::tokens::fungible::Balanced

pub trait Balanced<AccountId>: Inspect<AccountId> {
    type OnDropDebt: HandleImbalanceDrop<Self::Balance>;
    type OnDropCredit: HandleImbalanceDrop<Self::Balance>;

    // Required methods
    fn rescind(amount: Self::Balance) -> DebtOf<AccountId, Self>;
    fn issue(amount: Self::Balance) -> CreditOf<AccountId, Self>;
    fn slash(
        who: &AccountId,
        amount: Self::Balance
    ) -> (CreditOf<AccountId, Self>, Self::Balance);
    fn deposit(
        who: &AccountId,
        value: Self::Balance
    ) -> Result<DebtOf<AccountId, Self>, DispatchError>;
    fn withdraw(
        who: &AccountId,
        value: Self::Balance
    ) -> Result<CreditOf<AccountId, Self>, DispatchError>;

    // Provided methods
    fn pair(
        amount: Self::Balance
    ) -> (DebtOf<AccountId, Self>, CreditOf<AccountId, Self>) { ... }
    fn resolve(
        who: &AccountId,
        credit: CreditOf<AccountId, Self>
    ) -> Result<(), CreditOf<AccountId, Self>> { ... }
    fn settle(
        who: &AccountId,
        debt: DebtOf<AccountId, Self>
    ) -> Result<CreditOf<AccountId, Self>, DebtOf<AccountId, Self>> { ... }
}

A fungible token class where any creation and deletion of tokens is semi-explicit and where the total supply is maintained automatically.

This is auto-implemented when a token class has Unbalanced implemented.

Required Associated Types

type OnDropDebt: HandleImbalanceDrop<Self::Balance>

The type for managing what happens when an instance of Debt is dropped without being used.

type OnDropCredit: HandleImbalanceDrop<Self::Balance>

The type for managing what happens when an instance of Credit is dropped without being used.

Required Methods

fn rescind(amount: Self::Balance) -> DebtOf<AccountId, Self>

Reduce the total issuance by amount and return the according imbalance. The imbalance will typically be used to reduce an account by the same amount with e.g. settle.

This is infallible, but doesn’t guarantee that the entire amount is burnt, for example in the case of underflow.

fn issue(amount: Self::Balance) -> CreditOf<AccountId, Self>

Increase the total issuance by amount and return the according imbalance. The imbalance will typically be used to increase an account by the same amount with e.g. resolve_into_existing or resolve_creating.

This is infallible, but doesn’t guarantee that the entire amount is issued, for example in the case of overflow.

fn slash( who: &AccountId, amount: Self::Balance ) -> (CreditOf<AccountId, Self>, Self::Balance)

Deducts up to value from the combined balance of who. This function cannot fail.

The resulting imbalance is the first item of the tuple returned.

As much funds up to value will be deducted as possible. If this is less than value, then a non-zero second item will be returned.

fn deposit( who: &AccountId, value: Self::Balance ) -> Result<DebtOf<AccountId, Self>, DispatchError>

Mints exactly value into the account of who.

If who doesn’t exist, nothing is done and an Err returned. This could happen because it the account doesn’t yet exist and it isn’t possible to create it under the current circumstances and with value in it.

fn withdraw( who: &AccountId, value: Self::Balance ) -> Result<CreditOf<AccountId, Self>, DispatchError>

Removes value balance from who account if possible.

If the removal is not possible, then it returns Err and nothing is changed.

If the operation is successful, this will return Ok with a NegativeImbalance whose value is no less than value. It may be more in the case that removing it reduced it below Self::minimum_balance().

Provided Methods

fn pair( amount: Self::Balance ) -> (DebtOf<AccountId, Self>, CreditOf<AccountId, Self>)

Produce a pair of imbalances that cancel each other out exactly.

This is just the same as burning and issuing the same amount and has no effect on the total issuance.

fn resolve( who: &AccountId, credit: CreditOf<AccountId, Self> ) -> Result<(), CreditOf<AccountId, Self>>

The balance of who is increased in order to counter credit. If the whole of credit cannot be countered, then nothing is changed and the original credit is returned in an Err.

Please note: If credit.peek() is less than Self::minimum_balance(), then who must already exist for this to succeed.

fn settle( who: &AccountId, debt: DebtOf<AccountId, Self> ) -> Result<CreditOf<AccountId, Self>, DebtOf<AccountId, Self>>

The balance of who is decreased in order to counter debt. If the whole of debt cannot be countered, then nothing is changed and the original debt is returned in an Err.

Implementors

impl<AccountId, U: Unbalanced<AccountId>> Balanced<AccountId> for U

type OnDropCredit = DecreaseIssuance<AccountId, U>

type OnDropDebt = IncreaseIssuance<AccountId, U>