What's the difference between "btn.Click += new RoutedEventHandler (ButtonClick)" and "btn.Click += ButtonClick"?

Question

In C#, when registering a event handler, you have two options (btn is of type System.Windows.Controls.Button):

btn.Click += new RoutedEventHandler (ButtonClick) and

btn.Click += ButtonClick.

What's the semantic difference between them and their implications?

(The duplicate is for a different type, but it's the same basic question.) — Jon Skeet, Jun 18 '13 at 09:13
Indeed, I did not find these previous questions with my keywords. Thanks for pointing it out - I flagged it as a duplicate. — Daniel Albuschat, Jun 18 '13 at 09:21

score 7 · Accepted Answer · answered Jun 18 '13 at 09:21

The first version will compile without errors on all versions of .Net.

The second version will only compile on .Net 2 or later.

And that's the only difference. The second version is just some syntactic sugar introduced with .Net 2.

It's known as Method Group Conversion. See here for details:

http://mike-ward.net/blog/post/00020/anonymous-methods-method-group-conversions-and-eventhandler

score 3 · Answer 2 · answered Jun 18 '13 at 09:12

3

As I understood it, nothing, the compiler will infer the delegate type and wrap it for you automatically, it's just a shorthand way of doing it (because who really wants to type it all out).

answered Jun 18 '13 at 09:12

Lloyd

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basically, from what I just red, the syntax with new keyword works for framework 1.1, without it, it will give compiler error, that's why it is the default one in intellisense. – sameh.q Jun 18 '13 at 09:22
Yes I recall, because of that I tend to always do the long way. – Lloyd Jun 18 '13 at 09:27

score 1 · Answer 3 · answered Jun 18 '13 at 09:18

1

There is no differences. To understand these C# feature, you should read C# delegate and event keyword.

answered Jun 18 '13 at 09:18

min

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What's the difference between "btn.Click += new RoutedEventHandler (ButtonClick)" and "btn.Click += ButtonClick"?

3 Answers3