从另一个类更新类，封装问题 [英] Update class from another class, encapsulation issue

问题描述

$ p

在下面的例子中封装是坏的，因为传感器可以从任何其他类更新，不仅从设备。我是对的吗？

  class Device 
 {
 public IEnumerable< Sensor>传感器{get;私人集合
 
 void SomeInternalCall（int sensorId，int signal）
 {
 Sensors.First（s => s.Id == sensorId）.Update（signal）; 
} 
 
} 
 
 class传感器
 {
 public int Id {get;私人集合} 
 
 public event Action< int> OnSignal; 
 
 public void Update（int signal）
 {
 if（OnSignal！= null）OnSignal（signal）; 
} 
} 
 
 class SensorUser 
 {
 public SensorUser（传感器）
 {
 s.OnSignal + = SignalHandler ; 
} 
 
 void SignalHandler（int signal）
 {
 // ... 
} 
} 
  

解决方案

您可以创建一个提供只读访问的接口，并将其提供给 SensorUser ，而设备中的传感器实例集合 p>

 接口ISensor 
 {
 int Id {get; } 
事件Action< int> OnSignal; 
} 
 
 class传感器：ISensor 
 {
 public int Id {get;私人集合} 
 public event Action< int> OnSignal; 
 
 public void Update（int signal）
 {
 if（OnSignal！= null）OnSignal（signal）; 
} 
} 
 
 class SensorUser 
 {
 public SensorUser（ISensor s）
 {
 s.OnSignal + = SignalHandler ; 
} 
} 
  

How must I update a class, which must be updated only from another specific class?

In the following example encapsulation is broken, because Sensor can be updated from any other class, not only from Device. Am I right?

class Device
{
    public IEnumerable<Sensor> Sensors { get; private set; }

    void SomeInternalCall(int sensorId, int signal)
    {
        Sensors.First(s => s.Id == sensorId).Update(signal);
    }

}

class Sensor
{
    public int Id { get; private set; }

    public event Action<int> OnSignal;

    public void Update(int signal)
    {
        if (OnSignal != null) OnSignal(signal);
    }
}

class SensorUser
{
    public SensorUser(Sensor s)
    {
        s.OnSignal += SignalHandler;
    }

    void SignalHandler(int signal)
    {
        // ...
    }
}

解决方案

You can create an interface that provides read-only access and give it to SensorUser, while having a collection of Sensor instances in Device.

interface ISensor
{
    int Id { get;  }    
    event Action<int> OnSignal;
}

class Sensor : ISensor
{
    public int Id { get; private set; }    
    public event Action<int> OnSignal;

    public void Update(int signal)
    {
        if (OnSignal != null) OnSignal(signal);
    }
}

class SensorUser
{
    public SensorUser(ISensor s)
    {
        s.OnSignal += SignalHandler;
    }    
}

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