Linq to generic list?

in my DAL I have 3-5 Lists of something:

List<User>, List<Items>, List<bla&开发者_运维技巧gt;

Now I want to modify these Lists generic in a method.

How can I write a method with parameters allowed of all of this? (I tried var but don't allowed in the method head)

P.s.: Don't care about type, I will cast it back easily:

List<User> user; user = (List<User>)MethodName(user);

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Your question is somewhat vague, but I suspect you're looking for:

void SomeMethod(IList list)

If you're actually changing the list within the method, you don't need a return value.

An alternatively (a nicer one, frankly) is to make the method generic:

void SomeMethod<T>(IList<T> list)