Can you make an Extension Method Static/Shared?

问题

OK, I've probably misunderstood something here but, as far as I can see ...

• An extension method has to be contained in a module, not a class
• You can't make methods in modules Static/Shared
• Therefore you can't use an extension method on a class without instantiating it.

In other words you can't make an extension method on String called "MyExtensionMethod" and use:

String.MyExtensionMethod("String")

But instead ..

Dim test As String
test.MyExtensionMethod("string")

Is this correct? Or is there a way I can get extension methods to work as static methods?

回答1:

You are correct. Extension methods can only act on instances of a type.

And no, unfortunately there's no crafty way to write extension methods that act on the types themselves, behaving like static methods.

来源：https://stackoverflow.com/questions/2880773/can-you-make-an-extension-method-static-shared