Question

when implementing/using methods that return or work with instances of objects, what is the most elegant approach to check the function parameters ?

Method to call:

someType GetSomething(object x)
{
    if (x == null) {
        return;
    }

    //
    // Code...
    //
}

or better:

someType GetSomething(object x)
{
    if (x == null) {
        throw new ArgumentNullException("x");
    }

    //
    // Code...
    //
}

Calling Method:

void SomeOtherMethod()
{
    someType myType = GetSomething(someObject);

    if (someType == null) {
        return;
    }

}

or better:

void SomeOtherMethod()
{
    try {
        someType myType = GetSomething(someObject);
    } catch (ArgumentNullException) {
    }
}

When browsing through similar questions, the reason not to use try/catch is performance. But IMHO the try-catch just looks better :).

So, which way is more “elegant”?

Answer 1

If passing in a null is not valid, throw an exception (i.e. – this is an exceptional situation that should never happen).

If a null parameter is valid, return a corresponding object.

In general, accepting null parameters is bad practice – it goes against the principle of least surprise and requires the caller to know it is valid.