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c#eventsevent-handlingdelegates

What is the difference between "Action<object?, EventArgs>" and "EventHandler(object? sender, EventArgs e)"?

public delegate void Action<object?, EventArgs>(object? sender, EventArgs e);

public delegate void EventHandler(object? sender, EventArgs e);

What is the difference between those two lines? They seem to be functionally equal.

Solution

  • Rotabor's answer is basically correct, except for the reasoning: EventHandler exists since .NET Framework 1.1, which did not have generics and thus also did not yet have Action<T>. Only fully defined delegate types where allowed.

    When Action (with it's generic overloads) was added in .NET Framework 2.0, EventHandler was kept for backwards compatibility.