Struct wnf::DataAccessor

pub struct DataAccessor<'a, T>
where
    T: ?Sized,
{ /* private fields */ }

Available on crate feature subscribe only.

A handle to state data passed to state listeners

Listeners receive a DataAccessor<'a, T> in their StateListener::call method. It can be used to obtain the state data at the time the update took place.

The lifetime parameter 'a ties a DataAccessor<'a, T> to the lifetime of the state data, which is only valid within the scope of the call to the listener.

Implementations

impl<'a, T> DataAccessor<'a, T>

where T: ?Sized,

pub const fn cast<U>(self) -> DataAccessor<'a, U>

where U: ?Sized,

Casts the data type of this DataAccessor<'a, T> to a different type U

The returned DataAccessor<'a, U> represents the same underlying data, but treats them as being of a different type U.

pub const fn change_stamp(self) -> ChangeStamp

Queries the change stamp of this DataAccessor<'_, T>

The change stamp returned by this method is the change stamp of the underlying state for the update that caused the listener call to which this DataAccessor<'_, T> was passed. Note that in contrast to OwnedState::change_stamp or BorrowedState::change_stamp, this does not involve an OS call.

impl<T> DataAccessor<'_, T>

where T: Read<T>,

pub fn get(self) -> Result<T>

Queries the data of this DataAccessor<'_, T>

This produces an owned T on the stack and hence requires T: Sized. In order to produce a Box<T> for T: ?Sized, use the get_boxed method.

This returns the data of the accessor without a change stamp. In order to query both the data and the change stamp, use the query method.

The data returned by this method are the data of the underlying state for the update that caused the listener call to which this DataAccessor<'_, T> was passed. Note that in contrast to OwnedState::get or BorrowedState::get, this does not involve an OS call.

Errors

Returns an error if the queried data is not a valid T

pub fn query(self) -> Result<StampedData<T>>

Queries the data of this DataAccessor<'_, T> together with their change stamp

This produces an owned T on the stack and hence requires T: Sized. In order to produce a Box<T> for T: ?Sized, use the query_boxed method.

This returns the data of the accessor together with their change stamp as a StampedData<T>. In order to only query the data, use the get method.

The data returned by this method are the data of the underlying state for the update that caused the listener call to which this DataAccessor<'_, T> was passed. Note that in contrast to OwnedState::query or BorrowedState::query, this does not involve an OS call.

Errors

Returns an error if the queried data is not a valid T

impl<T> DataAccessor<'_, T>

where T: Read<Box<T>> + ?Sized,

pub fn get_boxed(self) -> Result<Box<T>>

Queries the data of this DataAccessor<'_, T> as a box

This produces a Box<T>. In order to produce an owned T on the stack (requiring T: Sized), use the get method.

This returns the data of the accessor without a change stamp. In order to query both the data and the change stamp, use the query_boxed method.

The data returned by this method are the data of the underlying state for the update that caused the listener call to which this DataAccessor<'_, T> was passed. Note that in contrast to OwnedState::get_boxed or BorrowedState::get_boxed, this does not involve an OS call.

Errors

Returns an error if the queried data is not a valid T

pub fn query_boxed(self) -> Result<StampedData<Box<T>>>

Queries the data of this DataAccessor<'_, T> as a box together with their change stamp

This produces a Box<T>. In order to produce an owned T on the stack (requiring T: Sized), use the query method.

This returns the data of the accessor together with their change stamp as a StampedData<Box<T>>. In order to only query the data, use the get_boxed method.

The data returned by this method are the data of the underlying state for the update that caused the listener call to which this DataAccessor<'_, T> was passed. Note that in contrast to OwnedState::query_boxed or BorrowedState::query_boxed, this does not involve an OS call.

Errors

Returns an error if the queried data is not a valid T

Trait Implementations

impl<T> Clone for DataAccessor<'_, T>

where T: ?Sized,

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T> Debug for DataAccessor<'_, T>

where T: ?Sized,

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

Formats the value using the given formatter.

impl<T> Copy for DataAccessor<'_, T>

where T: ?Sized,