Question

I am writing a program which will manipulate certain objects, let’s call them “Words”. Each word is an instance of one of several classes. There can be lots and lots of these at a time.

Each of these Word objects needs access to a dictionary, stored in an XML file. I don’t feel like each Word object should be loading the XML file separately. The Word objects should be able to access some global pool of program data.

What’s the best way to deal with this? Should I have a class called ProgramData which contains the XML document and gets passed to every Word object when they are created? This won’t cause multiple instances of the XML file to be loaded into memory, will it? Can I do what I want to do without passing ProgramData to every new object?

Answer 1

You should load the XML file into one instance of ProgramData, and then pass that instance into each Word instance (maybe in the constructor). You could also make a static property in the Word class that you set before you start instantiating Words, but be sure to use locking for thread safety.

Your alternative is the Singleton pattern, but trust me, you don’t want to go down that road.

Edit: Just to be clearer, this is the first option (the one I’d use):

public class Word
{
   private ProgramData _Data
   public Word(ProgramData data)
   {
      _Data = data;
   }

   public void MethodThatUsesData
   {
      // _Data.TryGetValue()
   }
}

// in your main method or initialization routine:
ProgramData data = MethodThatLoadsData();
Word w = new Word(data);