我有 3 个不同的类，具有相同的方法名称。 需要在使用前检查并应用它们的正确实例c#

Question

I have 3 different classes but the same methods inside them. Need to check before usage and apply the right instance of them c#. The calling methods are the same but different logic inside. I need to be able to call the right instance at the right time. I tried everything and it appears that I am failing.

Interface is not an option because these assemblies come in the form of DLLs. I dont have the source code for them.

public VersionAssembly240 obj1 = new VersionAssembly240();
public VersionAssembly250 obj2 = new VersionAssembly250();
public VersionAssembly260 obj3 = new VersionAssembly260();

void Main()
{
    ChooseRightInstance(null, obj2, null, "v25");

}

public void ChooseRightInstance(VersionAssembly240 obj1, VersionAssembly250 obj2, VersionAssembly260 obj3, string version)
{
    if (version == "v24")
    {
        var obj = obj1;
    }
    else if (version == "v25")
    {
        var obj = obj2;
    }
    else
    {
        var obj = obj3;
    }

    //I need to be able to access the obj var somce the 3 classess have the same access methods
    obj
}

//for testing
public class VersionAssembly260
{
    public string example()
    {
        return "v26";
    }
}

public class VersionAssembly250
{
    public string example()
    {
        return "v25";
    }
}

public class VersionAssembly240
{
    public string example()
    {
        return "v24";
    }
}

Answer 1

You have to crate an interface with method example() and different implementations for each class.

public interface IVersionAssembly
{
    string example();
}

Implement method example()

public class VersionAssembly260 : IVersionAssembly
{
    public string example()
    {
        return "v26";
    }
}

public class VersionAssembly250 : IVersionAssembly
{
    public string example()
    {
        return "v25";
    }
}

public class VersionAssembly240 : IVersionAssembly
{
    public string example()
    {
        return "v24";
    }
}

Now use interface IVersionAssembly in method ChooseRightInstance

public void ChooseRightInstance(VersionAssembly240 obj1, VersionAssembly250 obj2, VersionAssembly260 obj3, string version)
{
    IVersionAssembly obj;
    if (version == "v24")
    {
        obj = obj1;
    }
    else if (version == "v25")
    {
        obj = obj2;
    }
    else
    {
        obj = obj3;
    }

    obj.example();
}

Answer 2

You could potentially achieve this using an Interface, assuming that the real-world versions of these classes all have the same public methods.

Live demo: https://dotnetfiddle.net/63hjQt

Code. See the comments inline for more info on each important part:

using System;

public class Program
{
    public static void Main() {
      VersionAssembly240 obj1 = new VersionAssembly240();
      VersionAssembly250 obj2 = new VersionAssembly250();
      VersionAssembly260 obj3 = new VersionAssembly260();
      ChooseRightInstance( null, obj2,  null ,  "v25" );
    }

    public static void ChooseRightInstance(VersionAssembly240 obj1, VersionAssembly250 obj2, VersionAssembly260 obj3, string version) 
    {
      IVersionAssembly obj; //declare the object outside the if, as an instance of the interface
      if (version == "v24")
      {
        obj = obj1;
      }
      else if (version == "v25")
      {
        obj = obj2;
      }
      else
      {
        obj = obj3;
      }

      Console.WriteLine(obj.example()); //can call the example() method because the interface defines it
    } 
}

//interface which defines the methods which all the classes must implement    
public interface IVersionAssembly
{
    string example();
}

//all the classes implement the interface, but within the methods they can use different concrete implementations
public class VersionAssembly260 : IVersionAssembly
{
    public string example()
    {
        return "v26";
    }
}

public class VersionAssembly250 : IVersionAssembly
{
    public string example()
    {
        return "v25";
    }
}

public class VersionAssembly240 : IVersionAssembly
{
    public string example()
    {
        return "v24";
    }
}

Here's the Microsoft guide to interfaces in C#: https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/interfaces/

Answer 3

You can try below

// make abstract base class
public abstract class BaseVersionAssembly
{
    public abstract string example();
}

public class VersionAssembly260 : BaseVersionAssembly
{
    public override string example()
    {
        return "v26";
    }
}

public class VersionAssembly250 : BaseVersionAssembly
{
    public override string example()
    {
        return "v25";
    }
}

public class VersionAssembly240 : BaseVersionAssembly
{
    public override string example()
    {
        return "v24";
    }


}

ChooseRightInstance function

public string ChooseRightExample(BaseVersionAssembly obj)
{
    return obj.example();
}