Nullable不是泛型类, 但方法可以是泛型的;

Posted 2020-11-27 onecrazystone

注意where限制,防止用户输入struct或其它primitive类型

    public class Nullable
    {
        public Nullable();

        //
        // Summary:
        //     Creates an empty NullableRef<T> object which HasValue property is false.
        public static NullableRef<T> Create<T>() where T : class;
        //
        // Summary:
        //     Creates a non-empty NullableRef<T> object that holds reference to the given object
        //     t.
        public static NullableRef<T> Create<T>(T t) where T : class;
        //
        // Summary:
        //     Creates an empty SafeNullableRef<T> object which HasValue property is false.
        public static SafeNullableRef<T> CreateSafe<T>() where T : class, IDisposable;
        //
        // Summary:
        //     Creates a non-empty SafeNullableRef<T> object that holds reference to the given
        //     object t, and that takes responsibility for disposing the t object.
        public static SafeNullableRef<T> CreateSafe<T>(T t) where T : class, IDisposable;
    }
}