Trait Consideration
pub trait Consideration<AccountId, Footprint>:
Member
+ FullCodec
+ TypeInfo
+ MaxEncodedLen {
// Required methods
fn new(who: &AccountId, new: Footprint) -> Result<Self, DispatchError>;
fn update(
self,
who: &AccountId,
new: Footprint,
) -> Result<Self, DispatchError>;
fn drop(self, who: &AccountId) -> Result<(), DispatchError>;
fn ensure_successful(who: &AccountId, new: Footprint);
// Provided method
fn burn(self, _: &AccountId) { ... }
}Expand description
Some sort of cost taken from account temporarily in order to offset the cost to the chain of
holding some data Footprint in state.
The cost may be increased, reduced or dropped entirely as the footprint changes.
A single ticket corresponding to some particular datum held in storage. This is an opaque type, but must itself be stored and generally it should be placed alongside whatever data the ticket was created for and the attributable account.
Tickets are generally attributable to a single account for their whole lifetime. Calling
update, burn or drop with a different account than new was called with may result in
wrong accounting since the ticket type is not required to store the attributable account.
While not technically a linear type owing to the need for FullCodec, this should be
treated as one. Don’t type to duplicate it, and remember to drop it when you’re done with
it.
Required Methods§
fn new(who: &AccountId, new: Footprint) -> Result<Self, DispatchError>
fn new(who: &AccountId, new: Footprint) -> Result<Self, DispatchError>
Create a ticket for the new footprint attributable to who. This ticket must ultimately
be consumed through update or drop once the footprint changes or is removed.
fn update(self, who: &AccountId, new: Footprint) -> Result<Self, DispatchError>
fn update(self, who: &AccountId, new: Footprint) -> Result<Self, DispatchError>
Consume an old ticket to modify its footprint without altering the attributable account.
For creating tickets and dropping them, you can use the simpler new and drop instead.
Note that this must be called with the same account as new was.
fn drop(self, who: &AccountId) -> Result<(), DispatchError>
fn drop(self, who: &AccountId) -> Result<(), DispatchError>
Consume a ticket for some old footprint attributable to who which should now been freed.
fn ensure_successful(who: &AccountId, new: Footprint)
fn ensure_successful(who: &AccountId, new: Footprint)
Ensure that creating a ticket for a given account and footprint will be successful if done immediately after this call.
Provided Methods§
fn burn(self, _: &AccountId)
fn burn(self, _: &AccountId)
Consume a ticket for some old footprint attributable to who which should be sacrificed.
This is infallible. In the general case (and it is left unimplemented), then it is equivalent to the consideration never being dropped. Cases which can handle this properly should implement, but it MUST rely on the loss of the consideration to the owner.
Dyn Compatibility§
This trait is not dyn compatible.
In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.