C# 使用MDI表单实现命令模式

我需要一些建议。我只是想了解一下设计模式。 我试过寻找和阅读，但我觉得迷路了。 我真的希望你能给我一个建议

在这里，我尝试附加一些图片和我的代码：

接口

 public interface ICommand {
    void Execute();
 }

 public interface IDataManipulation {
    void Append();
    void Modify();
    void Remove();
 }

 public interface IDataReload {
    void Reload();
 }

合成对象

public class CommandDataManipulation : ICommand {
    private IDataManipulation __receiver;
    private DataManipulations __action;

    public CommandDataManipulation(IDataManipulation receiver, DataManipulations action) {
        __receiver = receiver ;
        __action = action;
    }

    public void Execute() {
        if (__receiver == null) return;
        if (__action == DataManipulations.Append) __receiver.Append();
        if (__action == DataManipulations.Modify) __receiver.Modify();
        if (__action == DataManipulations.Remove) __receiver.Remove();
    }
}

public class CommandDataReload : ICommand {
    private IDataReload     __receiver;

    public CommandDataReload(IDataReload receiver) {
        __receiver = receiver ;
    }

    public void Execute() {
        if (__receiver == null) return;
        __receiver.Reload();
    }
}

调用者

 public class InvokeDataCommand {

    private static InvokeDataCommand __instance;
    private ICommand __command;

    private InvokeDataCommand() {
         __instance = null;
     }

    public static InvokeDataCommand Instance() {
        if (__instance == null) {
            __instance = new InvokeDataCommand();
        }

        return __instance;
    }

    public void SetCommand(ICommand command) {
        __command = command;
    }

    public void ExecuteCommand() {
        __command.Execute();
    }
 }

接受者

public partial class Display : Form, IDataManipulation, IDataReload { 
  ...
}

我觉得除了使用命令外，我还使用了单例

我现在所做的是正确的吗

public partial class Display : Form, IDataManipulation, IDataReload { 
  ...
}