Dynamically apply multiple instances of an Attribute to a Property using a list

Question

I define multiple attributes on a class:

[CustomAttribute("a", state = 0)]
[CustomAttribute("b", state = 0)]
...
[CustomAttribute("z", state = 0)]
public class MyClass { ... }

The values ("a", "b", on through to "z") are also used elsewhere in the program, so right now, I have a duplicate array of names.

public static readonly string[] listOfNames = new [] { "a", "b", ..., "z" };

I can recover the names from the attributes using reflection to build listOfNames, but is there a way to do the reverse and define the attributes from listOfNames? I suspect not, but then is there a clearer way to at least avoid repeating the CustomAttribute bit?

Answer 1

You can use TypeDescriptor.AddAttributes to add class-level attributes to a type at run-time:

string[] listOfNames = new [] { "a", "b", "c" };
var attributes = listOfNames.Select(x=>new CustomAttribute(x)).ToArray();
TypeDescriptor.AddAttributes(typeof(MyClass), attributes);

Also as another option you can create a CustomTypeDescriptor for your type. In the custom type descriptor, you return custom PropertyDescriptor objects for the properties of your type and in the property descriptor, you return a custom set of attributes for the property. The key point in property descriptor is overriding Attributes property. Then create a TypeDescriptionProvider and register it for your type to provide the custom type description. This way you can use a single attribute instead of all those attributes.

To see an implementation take a look at this post: Combining Control Attributes.