Anonymous method in Invoke call

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Because Invoke/BeginInvoke accepts Delegate (rather than a typed delegate), you need to tell the compiler what type of delegate to create ; MethodInvoker (2.0) or Action (3.5) are common choices (note they have the same signature); like so:

control.Invoke((MethodInvoker) delegate {this.Text = "Hi";});

If you need to pass in parameters, then “captured variables” are the way:

string message = "Hi";
control.Invoke((MethodInvoker) delegate {this.Text = message;});

(caveat: you need to be a bit cautious if using captures async, but sync is fine – i.e. the above is fine)

Another option is to write an extension method:

public static void Invoke(this Control control, Action action)
{
    control.Invoke((Delegate)action);
}

then:

this.Invoke(delegate { this.Text = "hi"; });
// or since we are using C# 3.0
this.Invoke(() => { this.Text = "hi"; });

You can of course do the same with BeginInvoke:

public static void BeginInvoke(this Control control, Action action)
{
    control.BeginInvoke((Delegate)action);
}

If you can’t use C# 3.0, you could do the same with a regular instance method, presumably in a Form base-class.

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