How to create 2 generic class that will handle 2 different classes initialisation?

Question

I have 3 types of operation :Add,Multiply and Division

Below are the classes to handle this 3 operation:

public class Add
{
   public int Value {get;set;}
   public Add(int value)
   {
      Value=value;
   }
}

This below class will be called by above main class:

class Source : Add
{
   public Source(int value1)
          :base(value1)
   {
   }
}

class Destination : Add
{
    public Destination(int value2)
          :base(value2)
   {
   }
}

I am calling above class like this:

Add addObj1 = new Source(10);
Add addObj2 = new Destination(20);
int c=addObj1.Value + addObj2.Value;

Now i have another class like below:

public class Multiply
{
   public int Value {get;set;}
   public Multiply(int value)
   {
       Value=value;
   }
}

class Source1 : Multiply
{
   public Source(int value1)
          :base(value)
   {
   }
}

class Destination1 : Multiply
{
    public Destination1 (int value2)
          :base(int value2)
   {
   }
}

Now when i am trying to call this class like this:

Multiply multiplyObj1 = new Source(10); //This is always referring to Source of Add class
 Multiply multiplyObj2 = new Destination(5); //This is always referring to Destination of Add class

Now when i rename Source and Destination with Source1 and Destination1 and call like this then it is working:

Multiply multiplyObj1 = new Source1(10); //Working
Multiply multiplyObj2 = new Destination1(5); // Working
int c= multipleObj1.Value * multiplyObj2.Value;

Note:Right now i have created 4 class in which Source and Destination will handle Add class and Source1 and destination1 will handle Multiply

I am talking about how to reuse 2 class for both Add and Multiply class or for other class too(For Division etc..).

Now if i want to perform Division then i have again create 2 more class to handle division.

So here i dont want to duplicate Source and Destination i.e instead of creating 4 class i.e Source,Destination,Source1 and Destination1 is it possible to create only 2 generic class i.e Source and Destination that will perfectly handle both Add and Multiple???

Please post actual C# code. What kind of syntax is how you declare your classes... ?:( — Matías Fidemraizer, Aug 09 '16 at 10:30
@MatíasFidemraizer :Sorry but i have posted the code which i am using right now and i didnt got you what you are saying — I Love Stackoverflow, Aug 09 '16 at 10:37
@MatíasFidemraizer :Sorry there was some syntax mistake but now updated.Check now — I Love Stackoverflow, Aug 09 '16 at 11:28
BTW it has been already marked as a duplicate. If you find any other issue with your code you can post a new question :\ — Matías Fidemraizer, Aug 09 '16 at 14:06
@MatíasFidemraizer:But i dont have any issue with this code.It is just that i dont want to create duplicate class.So any idea or suggestion for this?? — I Love Stackoverflow, Aug 09 '16 at 14:08
Ok now I see why @Heinzi has marked it as duplicate. From your words, someone can understand that you want a way of deriving a class from two base classes. But you're asking for how to solve this with generics or with any other approach. — Matías Fidemraizer, Aug 09 '16 at 14:15
See my answer and let's discuss if it's what you're looking for with your question — Matías Fidemraizer, Aug 09 '16 at 14:21
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/120537/discussion-between-learning-and-matias-fidemraizer). — I Love Stackoverflow, Aug 09 '16 at 16:40

score 3 · Accepted Answer · edited Aug 10 '16 at 16:44

Let's summarize your issue now that you've already edited your question and you've added meaningful names to your classes.

You need to...

Perform additions.
Perform multiplications.

And you want to define base class to rule them all.

First of all, there's an issue here. You can't say that an addition source and a multiplication source are additions and multiplications altogether.

It's like saying that a cat is both an animal and a mineral. No, it's an animal.

This situation translated to object-oriented programming world means multiple inheritance:

// WRONG!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! C# doesn't support multiple inheritance
public class Source : Addition, Multiplication 
{
}

BTW, a source of additions couldn't also a source of multiplication. It's not a technical limitation, but a semantic limitation. It's just not right. Your design is simply wrong.

So, what? Well, I believe that you need to refactor your idea and code and you'll get what you want.

For example, if any math operation source has the same form, I would define a class to value sources:

public class Source
{
    public Source(int value) 
    {
         Value = value;
    }

    public int Value { get; }
}

And then I would define Multiply and Add classes based on an Operation class:

public abstract class Operation
{
      public Operation(Source sourceA, Source sourceB)
      {
           SourceA = sourceA;
           SourceB = sourceB;
      }

      public Source SourceA { get; }
      public Source SourceB { get; }

      public abstract int Do();
}

public class Add : Operation
{
      public Operation(Source sourceA, Source sourceB) : base(sourceA, sourceB)
      {
      }

      public override int Do() => SourceA.Value + SourceB.Value;
}

public class Multiply : Operation
{
      public Operation(Source sourceA, Source sourceB) : base(sourceA, sourceB)
      {
      }

      public override int Do() => SourceA.Value * SourceB.Value;
}

Now you've a single source for your mathematical operations and just a base class to summarize there what's common to any operation, and two operations already implemented.

Note that you can take advantage of polymorphism since any operation inherits Operation:

Source sourceA = new Source(203);
Source sourceB = new Source(134);

Operation op1 = new Multiply(sourceA, sourceB);
Operation op2 = new Add(sourceA, sourceB);

int result1 = op1.Do();
int result2 = op2.Do();

I believe that this could be a possible and acceptable design.

score 2 · Answer 2 · edited May 23 '17 at 12:14

Probably your actual use case doesn't love inheritance and you need to go with composition. Please double-check this other answer I did some days ago: Define a variable of one class from another class

Let's use a real-world case: a Car.

A Car has...

Engine
Radio
Wheel

It wouldn't be correct to say that a concrete Car should inherit Engine, Radio and Wheel, because a Car has them, but they're not cars, but parts of the whole Car.

When you arrive to this conclusion is because you need composition:

public class Car
{
     public Engine Engine { get; set; }
     public Wheel Wheel { get; set; }
     public Radio Radio { get; set; }
}

That way, a concrete car, let's say a Ferrari, can inherit everything a Car has by default and it can also add more components:

public class FerrariTestarossa : Car
{
     // More properties and methods that make a FerrariTestarossa unique
     // from a generic car
}

Probably you can extrapolate this to your own use case.

How to create 2 generic class that will handle 2 different classes initialisation?

2 Answers2