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


background: there developer principle "should function return null or throw exception if requested item not exist?" wouldn't discuss here. decided throw exception cases have return value , value wouldn't exist in cases of (programmatically or logically) invalid request.

and question: can mark function compiler knows never return null , warn checks if return value null?

you can using code contracts.

example : 

    public string method1()     {          contract.ensures(contract.result<string>() != null);          //     }

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