C#: Declare that a function will never return null?

Question

Background: There is this developer principle "Should my function return null or throw an exception if the requested item does not exist?" that I wouldn't like to discuss here. I decided to throw an exception for all cases that have to return a value and this value only wouldn't exist in cases of an (programmatically or logically) invalid request.

And finally my question: Can I mark a function so that the compiler knows that it will never return null and warn anybody who checks if the return value is null?

Answer 1

You can do this using Code Contracts.

Example :

    public String Method1()
    { 
        Contract.Ensures(Contract.Result<String>() != null);

        // To do
    }