Trait ValueStorage 

pub trait ValueStorage {
    type Value;

    // Required methods
    fn exists() -> bool;
    fn get() -> Option<Self::Value>;
    fn kill();
    fn mutate<R, F: FnOnce(&mut Option<Self::Value>) -> R>(f: F) -> R;
    fn put(value: Self::Value);
    fn set(value: Self::Value) -> Option<Self::Value>;
    fn take() -> Option<Self::Value>;

    // Provided method
    fn mutate_exists<R, F: FnOnce(&mut Self::Value) -> R>(f: F) -> Option<R> { ... }
}

Represents logic of managing globally stored value for more complicated logic.

In fact, represents custom implementation/wrapper around of Substrate’s ValueStorage with OptionQuery.

Required Associated Types

type Value

Stored value type.

Required Methods

fn exists() -> bool

Returns bool, defining does value present.

fn get() -> Option<Self::Value>

Gets stored value, if present.

fn kill()

Removes stored value.

fn mutate<R, F: FnOnce(&mut Option<Self::Value>) -> R>(f: F) -> R

Mutates stored value by Option reference, which stored (or not in None case) with given function.

May return generic type value.

fn put(value: Self::Value)

Stores given value.

fn set(value: Self::Value) -> Option<Self::Value>

Stores given value and returns previous one, if present.

fn take() -> Option<Self::Value>

Gets stored value, if present, and removes it from storage.

Provided Methods

fn mutate_exists<R, F: FnOnce(&mut Self::Value) -> R>(f: F) -> Option<R>

Works the same as Self::mutate, but triggers if value present.

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.

Implementors

impl<TIStorage, TIProvider> ValueStorage for TotalIssuanceWrap<TIStorage, TIProvider>

where TIStorage: TotalIssuanceStorage<TIProvider> + 'static, TIProvider: TotalIssuanceProvider + 'static,

Available on crate feature std only.

type Value = u64