Trait frame_support::traits::Currency

pub trait Currency<AccountId> {
    type Balance: AtLeast32BitUnsigned + FullCodec + Copy + MaybeSerializeDeserialize + Debug + Default;
    type PositiveImbalance: Imbalance<Self::Balance, Opposite = Self::NegativeImbalance>;
    type NegativeImbalance: Imbalance<Self::Balance, Opposite = Self::PositiveImbalance>;
    pub fn total_balance(who: &AccountId) -> Self::Balance;
    pub fn can_slash(who: &AccountId, value: Self::Balance) -> bool;
    pub fn total_issuance() -> Self::Balance;
    pub fn minimum_balance() -> Self::Balance;
    pub fn burn(amount: Self::Balance) -> Self::PositiveImbalance;
    pub fn issue(amount: Self::Balance) -> Self::NegativeImbalance;
    pub fn free_balance(who: &AccountId) -> Self::Balance;
    pub fn ensure_can_withdraw(
        who: &AccountId, 
        _amount: Self::Balance, 
        reasons: WithdrawReasons, 
        new_balance: Self::Balance
    ) -> DispatchResult;
    pub fn transfer(
        source: &AccountId, 
        dest: &AccountId, 
        value: Self::Balance, 
        existence_requirement: ExistenceRequirement
    ) -> DispatchResult;
    pub fn slash(
        who: &AccountId, 
        value: Self::Balance
    ) -> (Self::NegativeImbalance, Self::Balance);
    pub fn deposit_into_existing(
        who: &AccountId, 
        value: Self::Balance
    ) -> Result<Self::PositiveImbalance, DispatchError>;
    pub fn deposit_creating(
        who: &AccountId, 
        value: Self::Balance
    ) -> Self::PositiveImbalance;
    pub fn withdraw(
        who: &AccountId, 
        value: Self::Balance, 
        reasons: WithdrawReasons, 
        liveness: ExistenceRequirement
    ) -> Result<Self::NegativeImbalance, DispatchError>;
    pub fn make_free_balance_be(
        who: &AccountId, 
        balance: Self::Balance
    ) -> SignedImbalance<Self::Balance, Self::PositiveImbalance>;

    pub fn pair(
        amount: Self::Balance
    ) -> (Self::PositiveImbalance, Self::NegativeImbalance) { ... }
    pub fn resolve_into_existing(
        who: &AccountId, 
        value: Self::NegativeImbalance
    ) -> Result<(), Self::NegativeImbalance> { ... }
    pub fn resolve_creating(who: &AccountId, value: Self::NegativeImbalance) { ... }
    pub fn settle(
        who: &AccountId, 
        value: Self::PositiveImbalance, 
        reasons: WithdrawReasons, 
        liveness: ExistenceRequirement
    ) -> Result<(), Self::PositiveImbalance> { ... }
}

Abstraction over a fungible assets system.

Associated Types

type Balance: AtLeast32BitUnsigned + FullCodec + Copy + MaybeSerializeDeserialize + Debug + Default

The balance of an account.

type PositiveImbalance: Imbalance<Self::Balance, Opposite = Self::NegativeImbalance>

The opaque token type for an imbalance. This is returned by unbalanced operations and must be dealt with. It may be dropped but cannot be cloned.

type NegativeImbalance: Imbalance<Self::Balance, Opposite = Self::PositiveImbalance>

The opaque token type for an imbalance. This is returned by unbalanced operations and must be dealt with. It may be dropped but cannot be cloned.

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Required methods

pub fn total_balance(who: &AccountId) -> Self::Balance

The combined balance of who.

pub fn can_slash(who: &AccountId, value: Self::Balance) -> bool

Same result as slash(who, value) (but without the side-effects) assuming there are no balance changes in the meantime and only the reserved balance is not taken into account.

pub fn total_issuance() -> Self::Balance

The total amount of issuance in the system.

pub fn minimum_balance() -> Self::Balance

The minimum balance any single account may have. This is equivalent to the Balances module's ExistentialDeposit.

pub fn burn(amount: Self::Balance) -> Self::PositiveImbalance

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.

pub fn issue(amount: Self::Balance) -> Self::NegativeImbalance

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.

pub fn free_balance(who: &AccountId) -> Self::Balance

The 'free' balance of a given account.

This is the only balance that matters in terms of most operations on tokens. It alone is used to determine the balance when in the contract execution environment. When this balance falls below the value of ExistentialDeposit, then the 'current account' is deleted: specifically FreeBalance.

system::AccountNonce is also deleted if ReservedBalance is also zero (it also gets collapsed to zero if it ever becomes less than ExistentialDeposit.

pub fn ensure_can_withdraw(
    who: &AccountId,
    _amount: Self::Balance,
    reasons: WithdrawReasons,
    new_balance: Self::Balance
) -> DispatchResult

Returns Ok iff the account is able to make a withdrawal of the given amount for the given reason. Basically, it's just a dry-run of withdraw.

Err(...) with the reason why not otherwise.

pub fn transfer(
    source: &AccountId,
    dest: &AccountId,
    value: Self::Balance,
    existence_requirement: ExistenceRequirement
) -> DispatchResult

Transfer some liquid free balance to another staker.

This is a very high-level function. It will ensure all appropriate fees are paid and no imbalance in the system remains.

pub fn slash(
    who: &AccountId,
    value: Self::Balance
) -> (Self::NegativeImbalance, Self::Balance)

Deducts up to value from the combined balance of who, preferring to deduct from the free balance. 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.

pub fn deposit_into_existing(
    who: &AccountId,
    value: Self::Balance
) -> Result<Self::PositiveImbalance, DispatchError>

Mints value to the free balance of who.

If who doesn't exist, nothing is done and an Err returned.

pub fn deposit_creating(
    who: &AccountId,
    value: Self::Balance
) -> Self::PositiveImbalance

Adds up to value to the free balance of who. If who doesn't exist, it is created.

Infallible.

pub fn withdraw(
    who: &AccountId,
    value: Self::Balance,
    reasons: WithdrawReasons,
    liveness: ExistenceRequirement
) -> Result<Self::NegativeImbalance, DispatchError>

Removes some free balance from who account for reason if possible. If liveness is KeepAlive, then no less than ExistentialDeposit must be left remaining.

This checks any locks, vesting, and liquidity requirements. If the removal is not possible, then it returns Err.

If the operation is successful, this will return Ok with a NegativeImbalance whose value is value.

pub fn make_free_balance_be(
    who: &AccountId,
    balance: Self::Balance
) -> SignedImbalance<Self::Balance, Self::PositiveImbalance>

Ensure an account's free balance equals some value; this will create the account if needed.

Returns a signed imbalance and status to indicate if the account was successfully updated or update has led to killing of the account.

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Provided methods

pub fn pair(
    amount: Self::Balance
) -> (Self::PositiveImbalance, Self::NegativeImbalance)

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.

pub fn resolve_into_existing(
    who: &AccountId,
    value: Self::NegativeImbalance
) -> Result<(), Self::NegativeImbalance>

Similar to deposit_creating, only accepts a NegativeImbalance and returns nothing on success.

pub fn resolve_creating(who: &AccountId, value: Self::NegativeImbalance)

Similar to deposit_creating, only accepts a NegativeImbalance and returns nothing on success.

pub fn settle(
    who: &AccountId,
    value: Self::PositiveImbalance,
    reasons: WithdrawReasons,
    liveness: ExistenceRequirement
) -> Result<(), Self::PositiveImbalance>

Similar to withdraw, only accepts a PositiveImbalance and returns nothing on success.

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Implementors

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