>What's the best way to validate that all required properties on a class are completed correctly? The properties will eventually be
>mapped to UI fields, but the class itself is not visual. It's possible to instantiate the class, set some or all properties, and then call
>methods on it. I want to ensure that all required properties are complete before certain methods are run.
>
>The question is what to do if a required property is not set or is set wrong. Throw an exception?

From my own perception, high level classes should always work without throwing exception. In most of my classes, I have a lError and cError property. Once a method is completed, this can be validated against and see what went wrong, if applicable. Wherever as possible, a method should always return True or False. This is how I am trying to complete all my classes. As far as first level classes, or those included in the client application, I would say it depends on the requirements and how you would like to have it done.