How to change an instance at runtime?

How to change an instance at runtime?

• egghead2006

  Create an interface that is implemented by both classes and use that as a reference instead of both classes:

  interface IProvidesSingleDigitValue {      int getSingleDigitValue()      {         get;      } } class ClassOne : IProvidesSingleDigitValue {     public int getSingleDigitValue()     {         get { return 1; }     } } class ClassTwo : IProvidesSingleDigitValue {     public int getSingleDigitValue()     {         get { return 2; }     } } public void MyMethod(IProvidesSingleDigitValue obj) {     int i = obj.getSingleDigitValue(); }

  
  
  

• mattdawg

  Hi, i want a solution using other than interface.

  
  

• akodad

  Another solution would be to use a delegate. (Think of a delegate asa typesafe function pointer.) You could then select from between the two (or more) implementations. The only requirement for a delegate is that the method signatures match exactly. Even the names can be different. If you don't know the types/methods at compile-time, you may have to resort to reflection to identify the methods based on method signature, naming convention, or custom attribute.

   

  public class MyClass
  {

      public delegate int GetValue();
  

      public static void Main()
      {
          GetSingleDigitValue gsdv = new GetValue(ClassOne.GetSingleDigitValue);
          gsdv();
      }
  }
  
  public class ClassOne {
      public static int GetSingleDigitValue(){return 1;}
  }
  
  public class ClassTwo{
      public static int GetSingleDigitValue(){return 2;}
  }

  
  
  

• nick0123

  Depending on what exactly you're doing, you could also implement a Strategy pattern (http://www.dofactory.com/Patterns/PatternStrategy.aspx)

  That's a concept solution for ya ;)

  -E

  
  
  

• WereWolf

  Why don't you want to use interfaces They are specifically designed to allow different classes to provide common functionality, exactly what you want to do. Using David's example:

  interface IProvidesSingleDigitValue
  {
       int getSingleDigitValue()
       {
          get;
       }
  }
  class ClassOne : IProvidesSingleDigitValue
  {
      public int getSingleDigitValue()
      {
          get { return 1; }
      }
  }
  class ClassTwo : IProvidesSingleDigitValue
  {
      public int getSingleDigitValue()
      {
          get { return 2; }
      }
  }

  IProvidesSingleDigitValue c1;
  int _value;
  
  public void Choice_Click(...)
  {
      if (something)
          c1 = new ClassOne();
      else
          c1 = new ClassTwo();
  
      _value = c1.getSingleDigitValue();
  }
  

  
  

• spudstrawb

  Besides them inheriting off a common base class, the only other way I can think of is to use reflection:

  class ClassOne  {   public int GetValue()   {    return 1;   }  }  class ClassTwo  {   public int GetValue()   {    return 2;   }  }  public class ValueGetter  {   public static int GetValue(object obj)   {    MethodInfo method = obj.GetType().GetMethod("GetValue");    return (int)method.Invoke(obj, null);   }  }

  Basically the ValueGetter.GetValue method attempts to find a method called GetValue at runtime and invokes it (calls) and returns its result.

  
  
  
• How to change an instance at runtime?