Question

I got the following code the works :

var library = Assembly.LoadFrom(libraryPath);

var namespaces = library.GetTypes().GroupBy(t => t.Namespace);
foreach (var typesInNamespace in namespaces)
{
    foreach (var type in typesInNamespace)
    {
        [...]
    }
}

But when I want to test if the current Type is an Attribute with this code :

var attributes = typesInNamespace.Where(t => t is System.Attribute);

or

if (type is System.Attribute)

they both fail and I have the following warning :

The given expression is never of the provided ('System.Attribute') type

The classes are defined like this :

class ImportableModelAttribute : Attribute
{
}

class ImportableAttribute : Attribute
{
}

To be honest, I was expecting a sort of API to deal with Attributes (something like if (type.IsAtteribute)) but I didnt find anything, that’s why I’m trying to do it this way !

Answer 1

A Type itself is never an attribute (in the same way that typeof(string) isn’t a string), but I suspect you want:

if (typeof(Attribute).IsAssignableFrom(type))

(Or put that in a lambda experssion, of course.)

See the docs for Type.IsAssignableFrom for more information.