How to use the Factory Pattern with WPF

Question

I am stuck in a scenario where I can have many game screens, and I would like to be able to select a game screen using a radio button or with a combo box. But the problem is the best way to implement it?

Should I pass in the string of the checkbox or combobox selection to the Factory, or should I use an Enum? If the Enum is the way to go how do I use it? A simple example would be nice thanks.

Answer 1

I like using Enums instead of magical strings in this scenario, because it prevents problems caused by typos, and makes the options available to intellisense.

namespace TheGame 
{
    // declare enum with all available themes
    public enum EnumGameTheme { theme1, theme2 };

    // factory class
    public class ThemeFactory 
    {
        // factory method.  should create a theme object with the type of the enum value themeToCreate
        public static GameTheme GetTheme(EnumGameTheme themeToCreate) 
        {
            throw new NotImplementedException();
            // TODO return theme
        }
    }

    // TODO game theme class
    public class GameTheme { }
}

Code invoking the factory given a theme selected in (say) lstThemes:

// get the enum type from a string (selected item in the combo box)
TheGame.EnumGameTheme selectedTheme = Enum.Parse(typeof(TheGame.EnumGameTheme), (string)lstThemes.SelectedValue);
// invoke the factory method
TheGame.GameTheme newTheme = TheGame.ThemeFactory.GetTheme(selectedTheme);

Code to get available themes as strings:

// get a string array of all the game themes in the Enum (use this to populate the drop-down list)
string[] themeNames = Enum.GetNames(typeof(TheGame.EnumGameTheme));