Struct Change 

pub struct Change {
    pub components: Vec<u64>,
    pub label: &'static str,
    pub op: Op,
    pub prior: Option<Rc<dyn Any>>,
    pub value: Option<Rc<dyn Any>>,
    pub author: Option<&'static str>,
}

One announced change, in the form a store outside the UI can consume.

prior and value are the slot’s value before and after the write, captured only while a consumer that wants them is active (record_values, an UndoStack). A write with no such consumer clones nothing. They are type-erased; downcast with Change::prior_as / Change::value_as. A structural change carries positions as well: a Delete has the removed row in prior and its index (usize) in value, an Insert the added row in value and its index in prior, and a Move its index before and after.

Fields

components: Vec<u64>

The path’s components, outermost first: store, key, field, …

label: &'static str

The field’s name, which is also its column name.

op: Op

prior: Option<Rc<dyn Any>>

value: Option<Rc<dyn Any>>

author: Option<&'static str>

Who made it: None is the user; an undo replay stamps “undo”/“redo”; an importer its own name (with_author). Consumers can decline their own echoes.

Implementations

impl Change

pub fn prior_as<T>(&self) -> Option<&T>

where T: 'static,

The value before the write, if captured and of type T.

pub fn value_as<T>(&self) -> Option<&T>

where T: 'static,

The value after the write, if captured and of type T.

Trait Implementations

impl Clone for Change

fn clone(&self) -> Change

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Change

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

Formats the value using the given formatter.