Question

I’m trying to find the right thing to do with a non-null validation on a nullable boolean. I also want to be able to do the same thing with some other fields, including strings, ints, etc., so I want to use generics for the method. Here’s an example of the kind of thing which can happen.

bool? myValue = null;
bool valid = ValidateNotNull(myValue);

And here’s some validation code:

public bool ValidateNotNull<T>(T nullableField)
{
    return nullableField != null;
}

All the answers I’ve found to this kind of problem suggest adding a where T : struct or where T: class to the method signature, or using default(T) in the comparison, none of which will work for a bool where false is a valid value.

Any other suggestions? The code compiles, but Resharper isn’t happy about that null comparison on a value which it thinks might be a primitive, and I’d love to know what I should be doing to cheer it up.

NB: This isn’t the complete code. I’m still interested in maintaining the type. This is also not the only place I’ve run into the problem.

NB2: Yes, it compiles and works fine. What I really want to know is whether there is a code solution for stopping Resharper from complaining, or an idiomatic way to do this which I don’t know about.

Answer 1

Would comparing to default work?

    public bool ValidateNotNull<T>(T nullableField)
    {
        return Equals(nullableField, default(T));
    } 

Updated:

Either its a primitive, and all is well, or its not null:

    public bool ValidateNotNull<T>(T nullableField)
    {
        return typeof(T).IsPrimitive || !Equals(nullableField, null);
    }