Chapter 31: Using Progress<T> and IProgress<T>

Section 31.1: Simple Progress reporting

IProgress<T> can be used to report progress of some procedure to another procedure. This example shows how you can create a basic method that reports its progress.

void Main()

{

IProgress<int> p = new Progress<int>(progress =>

{

Console.WriteLine("Running Step: {0}", progress);

}); LongJob(p);

}

public void LongJob(IProgress<int> progress)

{

var max = 10;

for (int i = 0; i < max; i++)

{

progress.Report(i);

}

}

Output:

Running Step: 0

Running Step: 3

Running Step: 4

Running Step: 5

Running Step: 6

Running Step: 7

Running Step: 8

Running Step: 9

Running Step: 2

Running Step: 1

Note that when you this code runs, you may see numbers be output out of order. This is because the IProgress<T>.Report() method is run asynchronously, and is therefore not as suitable for situations where the progress must be reported in order.

Section 31.2: Using IProgress<T>

It's important to note that the System.Progress<T> class does not have the Report() method available on it. This method was implemented explicitly from the IProgress<T> interface, and therefore must be called on a

Progress<T> when it's cast to an IProgress<T>.

var p1 = new Progress<int>();

p1.Report(1); //compiler error, Progress does not contain method 'Report'

IProgress<int> p2 = new Progress<int>(); p2.Report(2); //works

var p3 = new Progress<int>(); ((IProgress<int>)p3).Report(3); //works