如何在Visual C＃2013中从另一个（引用的）项目访问表单组件？

Question

I'm trying to change the text in a RichTextBox in my "Game" project from another "Engine" project in Visual Studio community 2013, which is already referenced by the "Game" project. Everything I've tried to access it does not bring up the RichTextBox via Intellisense, causes a redline, and the "Engine" project refuses to build.

From checking around the site and Google, I've tried making the RichTextBox static and a few other tricks, including one I came up with myself- making a third project and referencing the other two. All to no avail.

Here should be the important parts of the code I have now:

in Game.cs, I have the class public:

namespace Game
{
    public partial class Game : Form
    {
        ...  //All the code for the form
    }
}

in Game.Designer.cs I have the RichTextBox public and static:

namespace Game
{
    partial class Game
    {
        ... // All the other unimportant stuff
        public static System.Windows.Forms.RichTextBox rtbMessages; //I've fixed the errors this caused in InitializeComponent() already
    }
}

Now from my "Engine" project, I'll try something like this (simplified but it shows what I'm trying to do):

using Game;

nameSpace Engine
{
    public class Monster
    {
        ... // Properties, Constructor, etc.

        public static bool IsDead(string name, int currentHP)
            if (currentHP <= 0)
            {
                Game.rtbMessages.Text += String.Format("You have killed {0}.{1}", name, Environment.NewLine);
                return true;
            }

            return false;
        }
    }
}

I've only been learning C# and Object-Oriented programming for 3 weeks now using basic tutorials I've been able to find online, but from what I've learned I honestly don't know why this won't work. I tried adding a reference from "Engine" back to "Game", but I get an error saying this would create a circular dependency since "Game" already references "Engine".

Is this even possible? I'm starting to wonder.

Edit: I made the mistake of assuming "Project" was just the name VS used for namespace. The problem isn't that they're in different namespaces, but different projects. Hence the strikeouts.

Answer 1

Dependancies (project references) should only be one-way. In fact VS tries very hard to make it impossible for you to create circular references, as you have found out.

Typically, a "Game" project will reference the "Engine" project. Not the other way around. An engine should never need to know about types in the game project.

If the engine does need to know about a game type then something is wrong with the architecture. Either the game type should actually be an engine type, or the functionality that you are coding into the engine is game-specific and should be in the game project.

In your case the functionality (updating the rtbMessages control) belongs in the game project. So from the game code you should do something like this:

if (Engine.Monster.IsDead("monster name", monster_hp)) {
    Game.rtbMessages.Text += String.Format("You have killed {0}.{1}", name, Environment.NewLine);
}

and remove the rtbMessages update from the Monster.IsDead function.

Additionally I would consider making another change.
Do you really need Monster.IsDead to be static? Presumably you have a reference to the monster already. A non-static IsDead method on the Engine.Monster type might make more sense. You could even make it a read-only property of the Engine.Monster class.