Why doesn't Dispatcher.BeginInvoke take an Action as a parameter?

Question

Dispatcher. Invoke method can take either a Delegate or Action instance as a parameter. But Dispatcher. BeginInvoke method doesn't accept an Action instance; it supports only Delegate .

It forces me to cast a lambda expression to Action in case of BeginInvoke. For example:

Dispatcher.Invoke(() => Title = "foo"); // success
// Dispatcher.BeginInvoke(() => Title = "foo"); // error
Dispatcher.BeginInvoke((Action)(() => Title = "foo")); // success

Is there any reason why Dispatcher.BeginInvoke method couldn't take an Action parameter?

Answer 1

It's a design decision. Since WPF came with .NET 3.0 and probably WPF was developed during some years, maybe delegates like Action , Action<T> ... or Func<T> ... weren't added in early .NET 3.0 alphas so they left the code using their own delegate.

In the other hand, you argue you need to perform a cast while you should instantiate Action instead:

// This is possible!
Delegate d1 = new Action(() => Console.WriteLine("hello world"));

Dispatcher.BeginInvoke(new Action(() => { /* ---do stuff--- */ }));