CODEWITHSUNDEEP
c#windows-8
Alex F
Alex F

Reputation: 43321

Windows.UI.Xaml.Application.Start method explanation

This code is from Programming Windows, Sixth Edition book:

using Windows.ApplicationModel.Activation; 
using Windows.UI; 
using Windows.UI.Xaml; 
using Windows.UI.Xaml.Controls; 
using Windows.UI.Xaml.Media;    

namespace StrippedDownHello
{
    public class App : Application
    {
        static void Main(string[] args)
        {
            Application.Start((p) => new App());
        }

        ...
    }
}

I cannot understand the syntax of Application.Start((p) => new App()); line. In the class documentation Start method is defined as: 

public static void Start(ApplicationInitializationCallback callback);

Please explain me how this code line with lambda expression is related to the Start method definition.

Upvotes: 2

Views: 844

Answers (1)

Julien
Julien

Reputation: 373

The lambda is just shortcut to write an instance of the ApplicationInitializationCallback

You can check the signature of this delegate and see that it indeed takes a parameter and return nothing.

In your example, the lambda is doing exactly this: takes a parameter p, instantiates an App and return nothing.

Without using lambda you would write it like this:

        static void Main(string[] args)
        {
            Application.Start(new ApplicationInitializationCallback(Start));
        }

        private static void Start(ApplicationInitializationCallbackParams p)
        {
            new App();
        }

Upvotes: 1

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