Class AsyncRelayCommandCommon

A reusable command that encapsulates the implementation of ICommand with support for async/await command delegates.
Enables instant creation of an ICommand without implementing the ICommand interface for each command. The AsyncRelayCommandCommon<TParam> accepts asynchronous command handlers and supports data bindng to properties like IsExecuting by implementing INotifyPropertyChanged.
Call and await the ExecuteAsync() method or one of its overloads to execute the command explicitly asynchronously. ICommand

Inheritance

Object

AsyncRelayCommandCommon

AsyncRelayCommand

AsyncRelayCommandCommon<TParam>

Implements

IAsyncRelayCommandCommon

ICommand

INotifyPropertyChanged

Inherited Members

Object.Equals(Object)

Object.Equals(Object, Object)

Object.GetHashCode()

Object.GetType()

Object.MemberwiseClone()

Object.ReferenceEquals(Object, Object)

Object.ToString()

Namespace: BionicCode.Utilities.Net

Assembly: BionicCode.Utilities.Net.Common.dll

Syntax

public abstract class AsyncRelayCommandCommon : IAsyncRelayCommandCommon, ICommand, INotifyPropertyChanged

Remarks

AsyncRelayCommandCommon implements ICommand. In case the AsyncRelayCommandCommon<TParam> is executed explicitly, especially with an asynchronous command handler registered, it is highly recommended to invoke the awaitable ExecuteAsync() or its overloads instead.

Constructors

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AsyncRelayCommandCommon()

Constructor

Declaration

protected AsyncRelayCommandCommon()

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AsyncRelayCommandCommon(Action)

Creates a new parameterless synchronous command that can always execute (CanExecute() will always return true).

Declaration

protected AsyncRelayCommandCommon(Action executeNoParam)

Parameters

Type	Name	Description
Action	executeNoParam	The awaitable execution handler.

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AsyncRelayCommandCommon(Action, Func<Boolean>)

Creates a new parameterless synchronous command.

Declaration

protected AsyncRelayCommandCommon(Action executeNoParam, Func<bool> canExecuteNoParam)

Parameters

Type	Name	Description
Action	executeNoParam	The execution handler.
Func<Boolean>	canExecuteNoParam	The execution status handler.

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AsyncRelayCommandCommon(Action<CancellationToken>)

Creates a new parameterless synchronous command that can always execute (CanExecute() will always return true)
and supports cancellation.

Declaration

protected AsyncRelayCommandCommon(Action<CancellationToken> executeNoParam)

Parameters

Type	Name	Description
Action<CancellationToken>	executeNoParam	The awaitable execution handler.

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AsyncRelayCommandCommon(Action<CancellationToken>, Func<Boolean>)

Creates a new parameterless synchronous command that supports cancellation.

Declaration

protected AsyncRelayCommandCommon(Action<CancellationToken> executeCancellable, Func<bool> canExecute)

Parameters

Type	Name	Description
Action<CancellationToken>	executeCancellable	The awaitable execution handler.
Func<Boolean>	canExecute	The can execute handler.

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AsyncRelayCommandCommon(Func<CancellationToken, Task>)

Creates a new parameterless asynchronous command that can always execute (CanExecute() will always return true)
and supports cancellation.

Declaration

protected AsyncRelayCommandCommon(Func<CancellationToken, Task> executeAsyncNoParam)

Parameters

Type	Name	Description
Func<CancellationToken, Task>	executeAsyncNoParam	The awaitable execution handler.

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AsyncRelayCommandCommon(Func<CancellationToken, Task>, Func<Boolean>)

Creates a new parameterless asynchronous command that supports cancellation and does not take a command parameter.

Declaration

protected AsyncRelayCommandCommon(Func<CancellationToken, Task> executeAsync, Func<bool> canExecute)

Parameters

Type	Name	Description
Func<CancellationToken, Task>	executeAsync	The awaitable execution handler.
Func<Boolean>	canExecute	The can execute handler.

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AsyncRelayCommandCommon(Func<Task>)

Creates a new parameterless asynchronous command that can always execute (CanExecute() will always return true).

Declaration

protected AsyncRelayCommandCommon(Func<Task> executeAsyncNoParam)

Parameters

Type	Name	Description
Func<Task>	executeAsyncNoParam	The awaitable execution handler.

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AsyncRelayCommandCommon(Func<Task>, Func<Boolean>)

Creates a parameterless new asynchronous command.

Declaration

protected AsyncRelayCommandCommon(Func<Task> executeAsyncNoParam, Func<bool> canExecuteNoParam)

Parameters

Type	Name	Description
Func<Task>	executeAsyncNoParam	The awaitable execution handler.
Func<Boolean>	canExecuteNoParam	The execution status handler.

Fields

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MaxThreads

The number of concurrent threads than can execute a command delegate.

Declaration

protected const int MaxThreads = 1

Field Value

Type	Description
Int32

Properties

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CanBeCanceled

Returns whether the command can be cancelled.

Declaration

public bool CanBeCanceled { get; }

Property Value

Type	Description
Boolean	`true` if cancellation is allowed. Otherwise `false`.

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CanExecuteNoParamDelegate

The registered parameterless CanExecute delegate.

Declaration

protected Func<bool> CanExecuteNoParamDelegate { get; }

Property Value

Type	Description
Func<Boolean>	`true` if the command can execute, otherwise `false`.

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CurrentCancellationToken

The currently used CancellationToken.

Declaration

public CancellationToken CurrentCancellationToken { get; }

Property Value

Type	Description
CancellationToken	A CancellationToken instance currently in use during the command execution.

Remarks

This property can be used to query the state of the cancellation or to register a cancellation callback by calling Register(Action).
The instance will change for each command execution.

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ExecuteAsyncNoParamDelegate

The registered parameterless async execute delegate.

Declaration

protected Func<Task> ExecuteAsyncNoParamDelegate { get; }

Property Value

Type	Description
Func<Task>	A delegate that takes no command parameter and returns a Task.

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ExecuteCancellableAsyncNoParamDelegate

The registered parameterless async execute delegate that supports cancellation.

Declaration

protected Func<CancellationToken, Task> ExecuteCancellableAsyncNoParamDelegate { get; }

Property Value

Type	Description
Func<CancellationToken, Task>	A delegate that supports cancellation, but takes no command parameter and returns a Task.

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ExecuteCancellableNoParamDelegate

The registered parameterless synchronous execute delegate that supports cancellation.

Declaration

protected Action<CancellationToken> ExecuteCancellableNoParamDelegate { get; }

Property Value

Type	Description
Action<CancellationToken>	A delegate that suppoprts cancellation, but takes no command parameter and returns void.

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ExecuteNoParamDelegate

The registered parameterless synchronous execute delegate.

Declaration

protected Action ExecuteNoParamDelegate { get; }

Property Value

Type	Description
Action	A delegate that takes no parameter and returns void.

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HasPending

Return whether the command has pending executions.

Declaration

public bool HasPending { get; }

Property Value

Type	Description
Boolean

Remarks

Only one command is executed at time. Sucessive command invocations are enqueued and run after the currently executing delegate has completed
or was cancelled.

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IsCancelled

Returns whether the command's executing operation was cancelled.

Declaration

public bool IsCancelled { get; }

Property Value

Type	Description
Boolean	`true` if the last command execution was cancelled. Otherwise `false`.

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IsExecuting

A flag to signal if the asynchronous operation has completed.

Declaration

public bool IsExecuting { get; }

Property Value

Type	Description
Boolean

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IsPendingCancelled

Returns whether the command's pending operations were cancelled.

Declaration

public bool IsPendingCancelled { get; }

Property Value

Type	Description
Boolean	`true` if the last command execution was cancelled. Otherwise `false`.

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PendingCount

Returns the number of pending command delegate executions.

Declaration

public int PendingCount { get; }

Property Value

Type	Description
Int32

Methods

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CancelAll()

Cancels all pending and executing commands.

Declaration

public void CancelAll()

Remarks

See Cancel() for the exception behavior of this overload.

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CancelAll(Boolean)

Cancels all pending and executing commands.

Declaration

public void CancelAll(bool throwOnFirstException)

Parameters

Type	Name	Description
Boolean	throwOnFirstException	See Cancel(Boolean) for the effects of the parameter.

Remarks

See Cancel(Boolean) for the exception behavior of this overload.

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CancelExecuting()

Cancels the currently executing command.

Declaration

public void CancelExecuting()

Remarks

See Cancel() for the exception behavior of this overload.

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CancelExecuting(Boolean)

Cancels the currently executing command.

Declaration

public void CancelExecuting(bool throwOnFirstException)

Parameters

Type	Name	Description
Boolean	throwOnFirstException	See Cancel(Boolean) for the effects of the parameter.

Remarks

See Cancel(Boolean) for the exception behavior of this overload.

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CancelPending()

Cancels all pending command executions.

Declaration

public void CancelPending()

Remarks

See Cancel() for the exception behavior of this overload.

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CancelPending(Boolean)

Cancels all pending command executions.

Declaration

public void CancelPending(bool throwOnFirstException)

Parameters

Type	Name	Description
Boolean	throwOnFirstException	See Cancel(Boolean) for the effects of the parameter.

Remarks

See Cancel(Boolean) for the exception behavior of this overload.

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CanExecute()

Determines whether this AsyncRelayCommandCommon can execute.

Declaration

public bool CanExecute()

Returns

Type	Description
Boolean	`true` if this command can be executed, otherwise `false`.

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ExecuteAsync()

Executes the AsyncRelayCommand on the current command target asynchronously.

Declaration

public async Task ExecuteAsync()

Returns

Type	Description
Task

Remarks

If the registered command handler is asynchronous (awaitable), then the execution is asynchronous otherwise the delegate is executed synchronously.

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ExecuteAsync(CancellationToken)

Executes the AsyncRelayCommand on the current command target asynchronously.

Declaration

public async Task ExecuteAsync(CancellationToken cancellationToken)

Parameters

Type	Name	Description
CancellationToken	cancellationToken	An instance of CancellationToken to cancel the executing command delegate.

Returns

Type	Description
Task

Remarks

If the registered command handler is asynchronous (awaitable), then the execution is asynchronous otherwise the delegate is executed synchronously.

Only one command is executed at time. Sucessive command invocations are enqueued and run after the currently executing delegate has completed
or was cancelled. Query HasPending to know if the command has pending delegate executions and PendingCount to knwo the number of pending delegate executions.

Exceptions

Type	Condition
OperationCanceledException	If executing command delegate was cancelled.

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ExecuteAsync(TimeSpan)

Executes the AsyncRelayCommand on the current command target asynchronously.

Declaration

public async Task ExecuteAsync(TimeSpan timeout)

Parameters

Type	Name	Description
TimeSpan	timeout	A TimeSpan to specify the timeout of the operation. A value of InfiniteTimeSpan (or a TimeSpan that represents -1) will specifiy an infinite time out. A value of Zero will cancel the operation immediately.

Returns

Type	Description
Task

Remarks

If the registered command handler is asynchronous (awaitable), then the execution is asynchronous otherwise the delegate is executed synchronously.

Exceptions

Type	Condition
OperationCanceledException	If the executing command delegate was cancelled.

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ExecuteAsync(TimeSpan, CancellationToken)

Executes the AsyncRelayCommand on the current command target asynchronously.

Declaration

public virtual async Task ExecuteAsync(TimeSpan timeout, CancellationToken cancellationToken)

Parameters

Type	Name	Description
TimeSpan	timeout	A TimeSpan to specify the timeout of the operation. A value of InfiniteTimeSpan (or a TimeSpan that represents -1) will specifiy an infinite time out. A value of Zero will cancel the operation immediately.
CancellationToken	cancellationToken	An instance of CancellationToken to cancel the executing command delegate.

Returns

Type	Description
Task

Remarks

If the registered command handler is asynchronous (awaitable), then the execution is asynchronous otherwise the delegate is executed synchronously.

Exceptions

Type	Condition
OperationCanceledException	If the executing command delegate was cancelled.
ArgumentOutOfRangeException	`timeout>>`.TotalMilliseconds is less than -1 or greater than MaxValue (or MaxValue - 1 on some versions of .NET). Note that this upper bound is more restrictive than MaxValue.

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InvalidateCommand()

Raises the CanExecuteChanged event of this particular command only.

Declaration

public void InvalidateCommand()

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OnCanExecuteChanged()

Raises the CanExecuteChanged event.

Declaration

protected virtual void OnCanExecuteChanged()

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OnPropertyChanged(String)

Raises the PropertyChanged event.

Declaration

protected virtual void OnPropertyChanged(string propertyName = "")

Parameters

Type	Name	Description
String	propertyName

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TryExecuteNoParamCommand()

Declaration

protected async Task<bool> TryExecuteNoParamCommand()

Returns

Type	Description
Task<Boolean>

Events

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CanExecuteChanged

Declaration

public event EventHandler CanExecuteChanged

Event Type

Type	Description
EventHandler

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PropertyChanged

Declaration

public event PropertyChangedEventHandler PropertyChanged

Event Type

Type	Description
PropertyChangedEventHandler

Explicit Interface Implementations

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ICommand.CanExecute(Object)

Declaration

bool ICommand.CanExecute(object parameter)

Parameters

Type	Name	Description
Object	parameter

Returns

Type	Description
Boolean

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ICommand.Execute(Object)

Declaration

async void ICommand.Execute(object parameter)

Parameters

Type	Name	Description
Object	parameter

Implements

IAsyncRelayCommandCommon

ICommand

INotifyPropertyChanged

Extension Methods

HelperExtensionsCommon.ToDictionary(Object)

HelperExtensionsCommon.ToFlatDictionary(Object)