Is it possible to write a extension for a typeparameter?

Question

I would like to convert this method

public static List<T> GetAllEnumValues<T>() where T : Enum
{
  return Enum.GetValues(typeof(T)).Cast<T>().ToList();
}

into a extension.

So that i can use it like this Countries.GetAllEnumValues(); instead of this GenericMethods.GetAllEnumValues<Countries>()

Is there a way to create an extension without passing an instance of the type to be extended?

I'd imagine something like this...

public static List<T> GetAllEnumValues<this T>() where T : Enum //not compiling for obvious reasons
{
  return Enum.GetValues(typeof(T)).Cast<T>().ToList();
}

Answer 1

No.

But you can import static members:

using static GenericMethods;

GetAllEnumValues<Countries>();

Also you can do it globally. For example in some other file like GlobalImports.cs:

global using static SomeNamespace.GenericMethods;

Or via .csproj:

<ItemGroup>
    <Using Include="SomeNamespace.GenericMethods" Static="True"/>
</ItemGroup>