代码之家 › 专栏 › 技术社区 › Dee

vb.net版班级组织

class vb.net

Dee · 技术社区 · 14 年前

我正在开发的应用程序有一个sub,它可以通过USB-to-GPIB接口控制一些不同的测试设备。

所以,我有:

Laptop
   USB - GPIB Interface
        Power Supply (Device Address 5)
        HP34970 Datalogger (Device Address 6)

在我的sub中,我想打开GPIB设备,发送几个SCPI命令来打开电源,再发送几个到HP34970来切换继电器或测量电压。

这里是我无法获得心智模型的地方-如果我创建了一个GPIB类的实例,并且有一个方法“打开”到GPIB总线的通道,那么我如何允许其他类(如powersupply)中的方法使用在GPIB类中创建的开放通道?例如,power supply类中用于设置电压的方法。

如果有人能花几分钟来发布伪代码和一些解释来说明我可以/应该如何组织这个,我将非常感谢您的帮助!

3 回复 | 直到 14 年前

veljkoz Danko Valkov 14 年前

把类本身看作设备。这里的主要好处是能够重用一次编写的代码—例如,您的所有设备都有地址,它们可以连接、测试连接、断开连接—为什么不在一个抽象的“设备”类中使用这些代码,并使所有设备从中继承?

public class DeviceTesting
{
   private string powerSupplyAddress = "DA5";
   private string dataLoggerAddress = "DA6";

   public static void main()
   {

      //bring interface into life
      DeviceInterface interface = GPIBInterface(); //example of inheritance - GPIB could be just one of the many device interfaces

      //the constructor in PowerSupply takes on the responsibility of initializing itself
      PowerSupply ps = new PowerSupply(powerSupplyAddress, interface); //plugged in with interface - has a reference to it
      //you could have multiple types of data loggers - all could inherit from DataLogger, and here so does HP34970
      //This means you can reuse the common code for data loggers, and write only the specifics for each specific device of that kind
      DataLogger myLogger = new HP34970(dataLoggerAddress, interface);


      //now, do whatever you do with the real devices
      ps.SetVoltage(220); //send voltage command directly
      interface.SendLogMessage("Interface is operational");
      interface.ExecuteTest("test1"); //send voltage command through interface
      //etc... you get the idea...
   }
}

现在,由于接口拥有与之接口的设备的知识,它必须在其构造函数中包含这些设备(在面向对象设计中,也称为依赖项注入,更具体地说,这里是构造函数注入):

public GPIBInterface : DeviceInterface //here we are reusing code that's same for all interfaces
{
    //whoever attaches to this interface is responsible for registering itself with it
    public PowerSupply Power{get;set;}
    public DataLogger Logger{get;set;}
    //notice here that it can work with any class that inherits from DataLogger
    public GPIBInterface()
    {

    }

    private override void TestInitialization() //as an example, we write our own testing by overriding some method in base class
    {
        base.TestInitialization(); //make sure that the base class checks it's ok - e.g. if it's own display is working or similar...

        if (Power.TestConnection() == false)
            throw new DeviceNotWorkingException(ps);
        if (Logger.TestConnection() == false)
            throw new DeviceNotWorkingException(_logger);
    }

    public void SendLogMessage(string message)
    {
        Logger.SendMessage(message);
    }

    public void ExecuteTest(string testName)
    {
        switch(testName)
        {
            case "test1":
                Power.SetVoltage(280);
                Logger.SendMessage("Voltage increased to 280V");
                break;
        }
    }
}

基本上,如果你的设备在“现实生活”中相互作用,那就意味着它们应该有一个相互连接的设备的引用。例如,如果您将PowerSupply直接插入到logger,那么PowerSupply类应该有对logger的引用。但是,如果它连接到接口,然后再连接到记录器,那么电源必须只引用接口而不是记录器(因为它没有连接到它)。

当你掌握了这一点,你的程序将真正受益于某种控制反转(IoC)模式——这样你就可以在一开始就定义什么是记录器,什么是电源,谁是显示器,什么时候有人需要某个特定的设备,IoC容器就会提供它。这样你就不必每次城里有新设备的时候都重写代码——只要用IoC容器注册新类型,一切就都正常了。

supercat 14 年前

Robert Harvey 14 年前

我如何允许其他方法类(如电源)来使用上课?

一种方法是创建一个复合类,其中包含powersupply类和GPIB类的实例(对于C#很抱歉):

public class PowerSupplyGPIBController
{
    // Members
    GPIB gpib;
    PowerSupply powerSupply;

    // Constructor
    public PowerSupplyGPIBController(GPIB myGPIB, PowerSupply myPowerSupply)
    {
        gpib = myGPIB;
        powerSupply = myPowerSupply;
    }

    // Method
    public void SendPowerSupplyVoltage()
    {
        GPIB.Send(myPowerSupply.Voltage);
    }
}