Struct ink_storage::Lazy

pub struct Lazy<T> where
    T: SpreadLayout,  { /* fields omitted */ }

A lazy storage entity.

This loads its value from storage upon first use.

Note

Use this if the storage field doesn't need to be loaded in some or most cases.

Implementations

impl<T> Lazy<T> where
    T: SpreadLayout, 

#[must_use]pub fn new(value: T) -> Self

Creates an eagerly populated lazy storage value.

#[must_use]pub fn lazy(key: Key) -> Self

Creates a true lazy storage value for the given key.

impl<T> Lazy<T> where
    T: SpreadLayout, 

#[must_use]pub fn get(lazy: &Self) -> &T

Returns a shared reference to the lazily loaded value.

Note

This loads the value from the contract storage if this did not happen before.

Panics

If loading from contract storage failed.

#[must_use]pub fn get_mut(lazy: &mut Self) -> &mut T

Returns an exclusive reference to the lazily loaded value.

Note

This loads the value from the contract storage if this did not happen before.

Panics

If loading from contract storage failed.

pub fn set(lazy: &mut Self, new_value: T)

Sets the value to value, without executing any reads.

Note

No reads from contract storage will be executed.

This method should be preferred over dereferencing or get_mut in case the returned value is of no interest to the caller.

Panics

If accessing the inner value fails.

Trait Implementations

impl<T> AsMut<T> for Lazy<T> where
    T: SpreadLayout, 

fn as_mut(&mut self) -> &mut T

Performs the conversion.

impl<T> AsRef<T> for Lazy<T> where
    T: SpreadLayout, 

fn as_ref(&self) -> &T

Performs the conversion.

impl<T> Borrow<T> for Lazy<T> where
    T: SpreadLayout, 

fn borrow(&self) -> &T

Immutably borrows from an owned value.

impl<T> BorrowMut<T> for Lazy<T> where
    T: SpreadLayout, 

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value.

impl<T: Debug> Debug for Lazy<T> where
    T: SpreadLayout, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Default for Lazy<T> where
    T: Default + SpreadLayout, 

fn default() -> Self

Returns the "default value" for a type.

impl<T> Deref for Lazy<T> where
    T: SpreadLayout, 

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<T> DerefMut for Lazy<T> where
    T: SpreadLayout, 

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<T> Display for Lazy<T> where
    T: Display + SpreadLayout, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Eq for Lazy<T> where
    T: Eq + SpreadLayout, 

impl<T> From<T> for Lazy<T> where
    T: SpreadLayout, 

fn from(value: T) -> Self

Performs the conversion.

impl<T> Hash for Lazy<T> where
    T: Hash + SpreadLayout, 

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given Hasher.

impl<T> Ord for Lazy<T> where
    T: Ord + SpreadLayout, 

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

#[must_use]fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

#[must_use]fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

#[must_use]fn clamp(self, min: Self, max: Self) -> Self

🔬 This is a nightly-only experimental API. (clamp)

Restrict a value to a certain interval.

impl<T> PartialEq<Lazy<T>> for Lazy<T> where
    T: PartialEq + SpreadLayout, 

fn eq(&self, other: &Self) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<T> PartialOrd<Lazy<T>> for Lazy<T> where
    T: PartialOrd + SpreadLayout, 

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Self) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Self) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn ge(&self, other: &Self) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

fn gt(&self, other: &Self) -> bool

This method tests greater than (for self and other) and is used by the > operator.

impl<T> SpreadLayout for Lazy<T> where
    T: SpreadLayout, 

const FOOTPRINT: u64

The footprint of the type.

fn pull_spread(ptr: &mut KeyPtr) -> Self

Pulls an instance of Self from the contract storage.

fn push_spread(&self, ptr: &mut KeyPtr)

Pushes an instance of Self to the contract storage.

fn clear_spread(&self, ptr: &mut KeyPtr)

Clears an instance of Self from the contract storage.

const REQUIRES_DEEP_CLEAN_UP: bool

Indicates whether a type requires deep clean-up of its state meaning that a clean-up routine has to decode an entity into an instance in order to eventually recurse upon its tear-down. This is not required for the majority of primitive data types such as i32, however types such as storage::Box that might want to forward the clean-up procedure to their inner T require a deep clean-up.

impl<T> StorageLayout for Lazy<T> where
    T: StorageLayout + SpreadLayout, 

fn layout(key_ptr: &mut KeyPtr) -> Layout

Returns the static storage layout of Self.