C# Subclass Best Practice

Question

I am currently working on a game in XNA and I'm not sure on how I should go about doing the following...

I have a base class of buildings as such

   public class BuildingsBase
   {
     private int _hp;
     public int hp
     {
        get { return _hp; }
        set { _hp= value; }
     }

     private int _woodRequired;
     public int woodRequired
     {
        get { return _woodRequired; }
        set { _woodRequired = value; }
     }
  }

I then have multiple subclasses for building types eg.

public class TownHall:BuildingsBase
{
    public int foodHeld;

    public TownHall()
    {
        foodHeld = 100;
        woodRequired = 500;
    }
}

My question is, what is the best way of setting the default values for building subclasses.

For example, the woodRequired for a townhall is set to 500 but at various places in code I need to access this value before I have an instance of townhall declared (When checking if there is enough wood to build).

I currently have a global array of default variables for each building type but im wondering if there is a better way of doing this.

if (Globals.buildingDefaults[BuildingType.Townhall].woodRequired < Globals.currentWood)
{
    Townhall newTH = new Townhall();
}

Answer 1

Usually what happens is that they create a flyweight (see pattern). This object contains properties that are the same for every instance anyway. There's no need to change (or actually store) the required amount of wood for each instance separately.

In a very basic design it would look like:

class BuildingTemplate
{
     public int WoodRequired { get; set; }
}

class Templates
{
    public static BuildingTemplate TownHall { get; set; }
}

In the end you'd be calling a method like:

public bool CanBuildTownHall(Player player)
{
    return player.HasEnoughResources(Templates.TownHall);
}

Of course, you can use a dictionary for template retrieval, and players shouldn't really know about building requirements. I'm just illustrating the pattern here.

If the player has enough resources, you can use the template to subtract the amount and create an actual instance of the TownHall. It's nice to have an reference to the actual template, because you'd probably be accessing other global properties that are valid for all TownHalls as well (such as audio/visuals/...).

class TownHall
{
    public TownHall(BuildingTemplate template)
    {
        _template = template;
    }
}