public static Task<TResult> Catch<TException, TResult>(
	this Task<TResult> task,
	Predicate<TException> filter,
	Func<Task<TResult>, TException, Task<TResult>> handler
)
where TException : Exception

<ExtensionAttribute>
Public Shared Function Catch(Of TException As Exception, TResult) ( 
	task As Task(Of TResult),
	filter As Predicate(Of TException),
	handler As Func(Of Task(Of TResult), TException, Task(Of TResult))
) As Task(Of TResult)

public:
[ExtensionAttribute]
generic<typename TException, typename TResult>
where TException : Exception
static Task<TResult>^ Catch(
	Task<TResult>^ task, 
	Predicate<TException>^ filter, 
	Func<Task<TResult>^, TException, Task<TResult>^>^ handler
)

[<ExtensionAttribute>]
static member Catch : 
        task : Task<'TResult> * 
        filter : Predicate<'TException> * 
        handler : Func<Task<'TResult>, 'TException, Task<'TResult>> -> Task<'TResult>  when 'TException : Exception

Parameters

task

Type: System.Threading.TasksTaskTResult
The antecedent task.

filter

Type: SystemPredicateTException
A predicate defining the condition under which the exception is handled.

handler

Type: SystemFuncTaskTResult, TException, TaskTResult
The exception handler continuation function to execute when task completes with an exception of type TException.

Type Parameters

TException

The type of exception which is handled by handler.

TResult

The result type of the antecedent task.

Return Value

Usage Note

This code implements support for the following construct without requiring the use of /.

try
{
    return await task.ConfigureAwait(false);
}
catch (TException ex) when (filter(ex))
{
    return await handler(task, ex).ConfigureAwait(false);
}

This method is capable of handling Canceled antecedent tasks when TException is assignable from TaskCanceledException.

This method ensures that exception information provided by a faulted or canceled task is not wrapped in an additional AggregateException.

Notes to Callers
Since the handler function is executed synchronously, this method should only be used for lightweight continuation functions. This restriction applies only to handler itself, not to the TaskTResult returned by it.

.NET for Windows Store apps

.NET Framework

Portable Class Library

Threading Library

Reference