Struct Slot 

pub struct Slot<T> {
    slot: U256,
    ctx: LayoutCtx,
    address: Address,
    _ty: PhantomData<T>,
}

Type-safe wrapper for a single EVM storage slot.

Type Parameters

• T: The Rust type stored in this slot (must implement Storable)

Example

// Generated by #[contract] macro:
pub mod slots {
    pub const NAME: U256 = uint!(2_U256);
}
let name_slot = Slot::<String>::new(slots::NAME);

The actual storage operations are handled by generated accessor methods that read/write values using the PrecompileStorageProvider trait.

Fields

slot: U256

ctx: LayoutCtx

address: Address

_ty: PhantomData<T>

Implementations

impl<T> Slot<T>

pub fn new(slot: U256, address: Address) -> Self

Creates a new Slot with the given slot number and address.

This is typically called with slot constants generated by the #[contract] macro. Creates a full-slot accessor. For packed fields, use new_at_loc instead.

pub fn new_with_ctx(slot: U256, ctx: LayoutCtx, address: Address) -> Self

Creates a new Slot with the given slot number, layout context, and address.

This is used by the handler system to create slots with specific packing contexts.

pub fn new_at_offset( base_slot: U256, offset_slots: usize, address: Address, ) -> Self

Creates a new Slot with the given base slot number with the given offset and address.

This is a convenience method for accessing struct fields. Creates a full-slot accessor. For packed fields, use new_at_loc instead.

pub fn new_at_loc(base_slot: U256, loc: FieldLocation, address: Address) -> Self

where T: StorableType,

Creates a new Slot from a FieldLocation generated by the #[derive(Storable)] macro.

This is the recommended way to access packed struct fields, combining slot offset and byte offset information in a type-safe manner.

This method should only be used with packable types (size < 32 bytes).

pub const fn slot(&self) -> U256

Returns the storage slot number where the underlying type is stored.

Multi-slot types use consecutive slots from this base slot.

pub const fn offset(&self) -> Option<usize>

Returns the byte offset within the slot (for packed fields).

Returns Some(offset) if this is a packed slot, None if it’s a full slot.

impl<T: Storable> Slot<T>

fn transient(&self) -> TransientOps

Returns a transient storage operations wrapper for this slot’s address.

Trait Implementations

impl<T: Clone> Clone for Slot<T>

fn clone(&self) -> Slot<T>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for Slot<T>

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

Formats the value using the given formatter.

impl<T: Storable> Handler<T> for Slot<T>

fn read(&self) -> Result<T>

Reads a value from storage at this slot.

This method delegates to the Storable::load implementation, which may read one or more consecutive slots depending on the type.

Uses thread-local storage context initialized by StorageCtx.

Example

let name_slot = Slot::<String>::new(slots::NAME, address_rc);
let name = name_slot.read().unwrap();

fn write(&mut self, value: T) -> Result<()>

Writes a value to storage at this slot.

This method delegates to the Storable::store implementation, which may write one or more consecutive slots depending on the type.

Uses thread-local storage context initialized by StorageCtx.

Example

let mut name_slot = Slot::<String>::new(slots::NAME, address_rc);
name_slot.write("MyToken".to_string()).unwrap();

fn delete(&mut self) -> Result<()>

Deletes the value at this slot (sets all slots to zero).

This method delegates to the Storable::delete implementation, which sets the appropriate slots to zero.

Uses thread-local storage context initialized by StorageCtx.

Example

let mut name_slot = Slot::<String>::new(slots::NAME, address_rc);
name_slot.delete().unwrap();

fn t_read(&self) -> Result<T>

Reads a value from transient storage at this slot.

fn t_write(&mut self, value: T) -> Result<()>

Writes a value to transient storage at this slot.

fn t_delete(&mut self) -> Result<()>

Deletes the value at this slot in transient storage (sets to zero).

impl<T> StorageOps for Slot<T>

fn load(&self, slot: U256) -> Result<U256>

Loads a value from the provided slot.

fn store(&mut self, slot: U256, value: U256) -> Result<()>

Stores a value at the provided slot.

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 64 bytes