Best Practice Question - Business Logic in Value Objects?

Just wondering what people's thoughts on best practices for setting properties of Value Objects.
For instance, I have several getter/setters in one of my Value Objects with logic in the setter that uses the value to set values of other properties.
For example, I have a Value Object that has the following properties:
category (of type Category, which is another Value Object with properties "name" and "id")
categoryId (of type int)
categoryUpdated (of type Boolean)
I have a collection of Category Objects in the Model. When I set the categoryId of this class, I set the "categoryUpdated" to true, and dispatch an CairngormEvent to that find the "category" with the specified "categoryId" and set the "category" property to this item.
So what is the best practice? To simply make the "categoryId" a public variable, and create a new Event/Command to perform all this logic? Or is it ok to do it all in the Value Object setter?
Thanks.

Hi Eric,
I can't speak for best practices, but the only logic I've ever added to a VO were getters: an example was a set of getters on an airline flight VO to get overall flight departure/arrival times/cities from an array of flight segments in a property of the VO.
I feel uneasy (in the nicest possible way) about your VO for two reasons: firstly it has a strong dependency on bits of the Cairngorm framework to look up the category (and VOs normally don't need to depend on anything), and secondly the intent of Commands in Cairngorm is more to represent user gestures than to wire up VO properties (I often see people shoehorning stuff into Commands that might be better of as plain old business utility classes). I would rather see an UpdateCategoryCommand (that's what the user is trying to do?) that updates categoryId and hits a delegate to populate the category property.
That said you might have a very good reason for doing this. Could you tell us where the code is that's setting categoryId, and if anything is using categoryUpdated?
Cheers,
Robin

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