Struct VersionedState 

pub struct VersionedState<S> {
    pub version: u32,
    pub data: S,
}

Version-tagged wrapper for serialized widget state.

When persisting state, the registry wraps the raw state in this envelope so it can detect schema version mismatches on restore.

Serialization

With the state-persistence feature enabled, VersionedState derives Serialize and Deserialize. Without the feature, it is a plain struct usable for in-memory versioning.

Fields

version: u32

Schema version (from Stateful::state_version()).

data: S

The actual state payload.

Implementations

impl<S> VersionedState<S>

pub fn new(version: u32, data: S) -> Self

Wrap state with its current version tag.

pub fn pack<W: Stateful<State = S>>(widget: &W) -> Self

Pack a widget’s state into a versioned envelope.

pub fn unpack<W: Stateful<State = S>>(self) -> Option<S>

Attempt to unpack, returning None if the version does not match the widget’s current state_version().

pub fn unpack_or_default<W: Stateful<State = S>>(self) -> S

where S: Default,

Unpack with fallback: returns the stored data if versions match, otherwise returns S::default().

impl<S> VersionedState<S>

pub fn unpack_with_migration<W>( self, chain: &MigrationChain<S>, ) -> RestoreResult<S>

where W: Stateful<State = S>, S: Default + 'static + Send,

Attempt to unpack with migration support.

If the stored version doesn’t match the current version, attempts to migrate through the provided chain. Falls back to default on failure.

Type Parameters

• W: The widget type that implements Stateful<State = S>.

Example

let chain = MigrationChain::new();
// ... register migrations ...

let versioned = load_state_from_disk();
let result = versioned.unpack_with_migration::<MyWidget>(&chain);
let state = result.into_state();

Trait Implementations

impl<S: Clone> Clone for VersionedState<S>

fn clone(&self) -> VersionedState<S>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<S: Debug> Debug for VersionedState<S>

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

Formats the value using the given formatter.

impl<S: Default> Default for VersionedState<S>

fn default() -> Self

Returns the “default value” for a type.