Question

I have read a bit about Design-Time Attributes for Components. There I found an attribute called CategoryAttribute. On that page it says that

The CategoryAttribute class defines the following common categories:

And then lists up a number of common categories. One of them are for example Appearance. I thought, brilliant! Then I can use [Category.Appearance] instead of [Category('Appearance')]! But apparently I couldn’t? Tried to write it, but Intellisense wouldn’t pick it up and it wouldn’t compile. Am I missing something here? Was it maybe not this those properties were for? If not, what are they for? If they are, how do I use them?

And yes, I do have the correct using to have access to the CategoryAttribute, cause [Category('Whatever')] do work. I’m just wondering how I use those defined common categories.

Answer 1

As you can see on MSDN it’s only a getter property, not a setter.

public static CategoryAttribute Appearance { get; } 

In fact, here’s what the code looks like using Reflector:

 public static CategoryAttribute Appearance     {         get         {             if (appearance == null)             {                 appearance = new CategoryAttribute('Appearance');             }             return appearance;         }     } 

So it doesn’t do a heck of a lot.

The only use I can see for it, is something like this:

            foreach (CategoryAttribute attrib in prop.GetCustomAttributes(typeof(CategoryAttribute), false))             {                 bool result = attrib.Equals(CategoryAttribute.Appearance);             } 

Basically, when using reflection to look at the class, you can easily check which category this belongs to without having to do a String comparison. But you can’t use it in the manner you’re trying to unfortunately.