Reactive

The Reactive class implements reactivity.

Reactive class

def __init__(
    self,
    default,
    *,
    layout=False,
    repaint=True,
    init=False,
    always_update=False,
    compute=True,
    recompose=False
):

Bases: Generic[ReactiveType]

Reactive descriptor.

Parameters

Parameter	Default	Description
default ReactiveType | Callable[[], ReactiveType]	required	A default value or callable that returns a default.
layout bool	False	Perform a layout on change.
repaint bool	True	Perform a repaint on change.
init bool	False	Call watchers on initialize (post mount).
always_update bool	False	Call watchers even when the new value equals the old value.
compute bool	True	Run compute methods when attribute is changed.
recompose bool	False	Compose the widget again when the attribute changes.

owner property

owner: Type[MessageTarget]

The owner (class) where the reactive was declared.

ReactiveError class

Bases: Exception

Base class for reactive errors.

TooManyComputesError class

Bases: ReactiveError

Raised when an attribute has public and private compute methods.

reactive class

def __init__(
    self,
    default,
    *,
    layout=False,
    repaint=True,
    init=True,
    always_update=False,
    recompose=False
):

Bases: Reactive[ReactiveType]

Create a reactive attribute.

Parameters

Parameter	Default	Description
default ReactiveType | Callable[[], ReactiveType]	required	A default value or callable that returns a default.
layout bool	False	Perform a layout on change.
repaint bool	True	Perform a repaint on change.
init bool	True	Call watchers on initialize (post mount).
always_update bool	False	Call watchers even when the new value equals the old value.

var class

def __init__(self, default, init=True, always_update=False):

Bases: Reactive[ReactiveType]

Create a reactive attribute (with no auto-refresh).

Parameters

Parameter	Default	Description
default ReactiveType | Callable[[], ReactiveType]	required	A default value or callable that returns a default.
init bool	True	Call watchers on initialize (post mount).
always_update bool	False	Call watchers even when the new value equals the old value.

await_watcher async

def await_watcher(obj, awaitable):

Coroutine to await an awaitable returned from a watcher

invoke_watcher function

def invoke_watcher(
    watcher_object, watch_function, old_value, value
):

Invoke a watch function.

Parameters

Parameter	Default	Description
watcher_object Reactable	required	The object watching for the changes.
watch_function WatchCallbackType	required	A watch function, which may be sync or async.
old_value object	required	The old value of the attribute.
value object	required	The new value of the attribute.