Can I initialize a C# attribute with an array or other variable number of arguments?

Question

Is it possible to create an attribute that can be initialized with a variable number of arguments?

For example:

[MyCustomAttribute(new int[3,4,5])]           


        

Answer 1

You can do it, but it isn't CLS compliant:

[assembly: CLSCompliant(true)]

class Foo : Attribute
{
    public Foo(string[] vals) { }
}
[Foo(new string[] {"abc","def"})]
static void Bar() {}

Shows:

Warning 1   Arrays as attribute arguments is not CLS-compliant

For regular reflection usage, it may be preferable to have multiple attributes, i.e.

[Foo("abc"), Foo("def")]

However, this won't work with TypeDescriptor/PropertyDescriptor, where only a single instance of any attribute is supported (either the first or last wins, I can't recall which).