Question

Given a collection

IEnumerable<Type> supportedTypes

What’s the best way to check whether a given object is one of those types (or a derived type)?

My first instinct was to do something like:

// object target is a parameter passed to the method in which I'm doing this.
if (supportedTypes.Count( supportedType => target is supportedType ) > 0)
{
    // Yay my object is of a supported type!!!
}

..but that doesn’t seem to be working. Can I not use the “is” keyword in a lambda expression like this?

Answer 1

OK so in the course of typing the question and doing some more experimenting to make sure I wasn’t asking something really stupid, I realized an easy solution. Posting here in case somebody else ever does something equally stupid. 😉

You can’t use the “is” keyword in your lambda expression, but you can use:

supportedType => supportedType.IsInstanceOfType(target)

yielding:

if (supportedTypes.Count( supportedType => 
supportedType.IsInstanceOfType(target)) > 0)

if (supportedTypes.Any( supportedType => 
                              supportedType.IsInstanceOfType(target)))
// object target is a parameter passed to the method in which I'm doing this.
{
    // Yay my object is of a supported type!!!
}

hat-tip to Bob Vale for noting in the comments below that I should have been using .Any(…) rather than .Count(…) > 0