Method Finally

Finally<TSource>(IEnumerable<TSource>, Action)

Creates a sequence whose termination or disposal of an enumerator causes a finally action to be executed.

Declaration

public static IEnumerable<TSource> Finally<TSource>(this IEnumerable<TSource> source, Action finallyAction)

Parameters

Type	Name	Description
IEnumerable<TSource>	source	Source sequence.
Action	finallyAction	Action to run upon termination of the sequence, or when an enumerator is disposed.

Returns

Type	Description
IEnumerable<TSource>	Source sequence with guarantees on the invocation of the finally action.

Type Parameters

Name	Description
TSource	Source sequence element type.

Remarks

This method uses deferred execution and streams its results.

Examples

The following code example demonstrates how to execute an action when an enumeration completes, using Finally.

var sequence = Enumerable.Range(1, 5);
            
// Execute an action when enumeration is complete, regardless of success or fail.
var result = sequence
    .Do(i => Console.Write($"{i}, "))
    .Finally(() => Console.WriteLine("Completed"));

result.Consume();

// This code produces the following output:
// 1, 2, 3, 4, 5, Completed

Exceptions

Type	Condition
ArgumentNullException	source or finallyAction is null.