c# - Event declaration with assignment to empty delegate

Question

I have question on a piece of code I often stumble across online. For example

  public static event Action<Foo> foo = delegate{  };

I got the left hand side of the declaration. But the right hand side is confusing. What is the point in assigning the event to a delegate with empty parenthesis?

Answer 1

UPDATE: in modern versions of C#, the recommended pattern to use is to leave it as null and use the ?. operator:

event Action<Foo> foo; // leave it as null as the default
// ...
foo?.(new Foo());

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In older versions of C#, the reason for this pattern could be that the default value of an event field is null. This requires the use of a null-check every-time you want to raise the event - calling foo() on an uninitialised event field would result in a NullReferenceException. It's more convenient to just give it a sensible default value like a no-op, that way you can raise the event directly without having to use a wrapper method or anything.