55 lines
3.0 KiB
C#
55 lines
3.0 KiB
C#
// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT license.
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// See the LICENSE file in the project root for more information.
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using System;
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namespace CommunityToolkit.Mvvm.Input;
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/// <summary>
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/// Options to customize the behavior of <see cref="AsyncRelayCommand"/> and <see cref="AsyncRelayCommand{T}"/> instances.
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/// </summary>
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[Flags]
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public enum AsyncRelayCommandOptions
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{
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/// <summary>
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/// No option is specified. The <see cref="AsyncRelayCommand"/> and <see cref="AsyncRelayCommand{T}"/> types will use their default behavior:
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/// <list type="bullet">
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/// <item>Concurrent execution is disallowed: a command is disabled if there is a pending asynchronous execution running.</item>
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/// <item>
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/// <para>
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/// Exceptions are thrown on the calling context: calling <see cref="AsyncRelayCommand.Execute(object?)"/> will await the
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/// returned <see cref="System.Threading.Tasks.Task"/> for the operation, and propagate the exception on the calling context.
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/// </para>
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/// <para>This behavior is consistent with synchronous commands, where exceptions in <see cref="RelayCommand.Execute(object?)"/> behave the same.</para>
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/// </item>
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/// </list>
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/// </summary>
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None = 0,
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/// <summary>
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/// <para>Concurrent executions are allowed. This option makes it so that the same command can be invoked concurrently multiple times.</para>
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/// <para>
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/// Note that additional considerations should be taken into account in this case:
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/// <list type="bullet">
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/// <item>If the command supports cancellation, previous invocations will automatically be canceled if a new one is started.</item>
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/// <item>The <see cref="AsyncRelayCommand.ExecutionTask"/> property will always represent the operation that was started last.</item>
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/// </list>
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/// </para>
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/// </summary>
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AllowConcurrentExecutions = 1 << 0,
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/// <summary>
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/// <para>Exceptions are not thrown on the calling context, and are propagated to <see cref="System.Threading.Tasks.TaskScheduler.UnobservedTaskException"/> instead.</para>
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/// <para>
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/// This affects how calls to <see cref="AsyncRelayCommand.Execute(object?)"/> behave. When this option is used, if an operation fails, that exception will not
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/// be rethrown on the calling context (as it is not awaited there). Instead, it will flow to <see cref="System.Threading.Tasks.TaskScheduler.UnobservedTaskException"/>.
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/// </para>
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/// <para>
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/// This option enables more advanced scenarios, where the <see cref="AsyncRelayCommand.ExecutionTask"/> property can be used to inspect the state of an operation
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/// that was queued. That is, even if the operation failed or was canceled, the details of that can be retrieved at a later time by accessing this property.
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/// </para>
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/// </summary>
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FlowExceptionsToTaskScheduler = 1 << 1
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}
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