Flyweight pattern dilemma

Question

This Flyweight DP tutorial shows a good explanation of the Flyweight pattern.

Anyway, let's say that we want to change the font size of the this.height = 200; (assume that the properties are not protected). That means that all the font sizes will be changed since objects are of reference type.

Let's say that this is a text editor, and we want to change the font size only for a specific letter (single instance of the letter, not all). So now a problem occurs since if we somehow change the font size of the object in the dictionary, all of the occurrences will be changed. How can I deal with this?

Answer 1

I think this is a solution that might fit. It is a flyweight inside a flyweight, but in C#, it is a little bit simplified but I think you should get the concept. The idea is to put a facade in place to get the parametrized classes. Inside that facade i have a dictionary that makes new factories for new fontsizes. This might seem weird, but beware that the flyweight is a creational design pattern, it will not store the text itself, only give you access to the same objects. And the state is obviously not the same, so i think a different factory might be justifiable.

    public class AlphabetFacade
    {
        private Dictionary<int, AlphabetFactory> _alphabetFactories = new Dictionary<int, AlphabetFactory>();

        private Character GetChar(string character, int fontSize)
        {
            if (_alphabetFactories.ContainsKey(fontSize)) return _alphabetFactories[fontSize].GetCharacter(character);
            var factoryNew = new AlphabetFactory(fontSize);
            _alphabetFactories.Add(fontSize, factoryNew);
            return factoryNew.GetCharacter(character);
        }
    }

    internal class AlphabetFactory
    {
        private readonly int _fontSize;

        private readonly Dictionary<string, Character> _characters = new Dictionary<string, Character>();

        public AlphabetFactory(int fontSize)
        {
            _fontSize = fontSize;
        }

        public Character GetCharacter(string character)
        {
            if (_characters.ContainsKey(character)) return _characters[character];
            var characterNew = new Character(_fontSize, character);
            _characters.Add(character, characterNew);
            return characterNew;
        }
    }

     class Character
     {
         public Character(int size, string @char)
         {
            Size = size;
            Char = @char;
         }

         public int Size { get; }
         public string Char { get; }
     }