Question

I have a class on which I want to allow several (~20+) configuration options. Each option turns on or off a piece of functionality, or otherwise alters operations. To facilitate this, I coded a separate options class with default values. However, I had to litter my code with guard conditions to determine how methods should behave. I am almost done, but now the code seems to smell.

Is there a preferred method/pattern to implement a class like this?

EDIT: More specifically, I am working on a parsing class. Each option configures mutually exclusive portions of the basic parsing algorithm. For example I have several areas in my class that look like the below:

 if (this.Option.UseIdAttribute)       attributeIDs = new Hashtable();  else       attributeIDs = null;       public Element GetElementById(string id)     {         if (string.IsNullOrEmpty (id))             throw new ArgumentNullException('id');          if (attributeIDs == null)             throw new Exception(ExceptionUseIdAttributeFalse);          return attributeIDs[id.ToLower()] as Element;     } 

Answer 1

How about the Decorator pattern? It’s designed for dynamically adding behavior to a class.