AsyncAtom<T> class

Namespace: Arlecchino.Atoms · Assembly: Arlecchino

A value produced by background work, with its progress exposed as state for a view to draw. Results are handed back on the drawing thread, and a new load cancels the one before it.

public sealed class AsyncAtom<T> : IReadableAtom<T>

Implements IReadableAtom<T>

Constructors

Member	Summary
AsyncAtom(T)	Creates the state, without starting anything.

Properties

Member	Summary
Error	What the last load threw, or null when it did not fail.
IsLoading	Whether a load is running right now.
Status	Progress of the last load, for showing a spinner or an error.
Value	The last loaded value. It stays put while a new load runs, so the view keeps its content.

Methods

Member	Summary
Cancel()	Abandons the running load, keeping whatever was loaded before it. The state stops reporting itself as loading, so a spinner bound to it stops.
Load(Func<CancellationToken, Task<T>>)	Starts work in the background, canceling whatever was already running. Returns at once; the result, or the failure, arrives later on the UI thread.
Subscribe(Action)	Watches for a new value. Progress changes on their own do not notify.
SubscribeToStatus(Action)	Watches progress, which is what a spinner or an error line needs.

Constructors in detail

AsyncAtom(T)

public AsyncAtom(T initial);

Creates the state, without starting anything.

Parameters

Name	Type	Description
initial	T	What to hold until the first load finishes.

Properties in detail

Error

public IReadableAtom<Exception> Error { get; }

What the last load threw, or null when it did not fail.

Type IReadableAtom<Exception>

IsLoading

public bool IsLoading { get; }

Whether a load is running right now.

Type bool

Status

public IReadableAtom<LoadStatus> Status { get; }

Progress of the last load, for showing a spinner or an error.

Type IReadableAtom<LoadStatus>

Value

public T Value { get; }

The last loaded value. It stays put while a new load runs, so the view keeps its content.

Type T

Methods in detail

Cancel()

public void Cancel();

Abandons the running load, keeping whatever was loaded before it. The state stops reporting itself as loading, so a spinner bound to it stops.

Load(Func<CancellationToken, Task<T>>)

public void Load(Func<CancellationToken, Task<T>> load);

Starts work in the background, canceling whatever was already running. Returns at once; the result, or the failure, arrives later on the UI thread.

Parameters

Name	Type	Description
load	Func<T, TResult><CancellationToken, Task<TResult><T>>	The work to run, given a token that is canceled when a newer load starts.

Subscribe(Action)

public IDisposable Subscribe(Action listener);

Watches for a new value. Progress changes on their own do not notify.

Parameters

Name	Type	Description
listener	Action	Called after the value changes.

Returns IDisposable — Dispose to stop listening.

SubscribeToStatus(Action)

public IDisposable SubscribeToStatus(Action listener);

Watches progress, which is what a spinner or an error line needs.

Parameters

Name	Type	Description
listener	Action	Called after the status changes.

Returns IDisposable — Dispose to stop listening.