How to clean up if else series

Question

Work in C#, want to reduce if else series, entity have two property FromServiceID and ToServiceID ,suppose my ServiceClass instanc

Answer 1

You can use switch case as below:

var entity = new ServiceClass();

entity.FromServiceID = 3;
entity.ToServiceID = 1;

switch(entity.FromServiceID)
{
    case 1:
        new 1KWithdrawal();
        break;
    case 2:
        new 10KWithdrawal();
        break;
    case 3:
        new BTWithdrawal();
        break;
}

switch(entity.ToServiceID)
{
    case 1:
        new 1KDeposit();
        break;
    case 2:
        new 10KDeposit();
        break;
    case 3:
        new BTDeposit();
        break;
}

Answer 2

Maybe this is an overkill, but you can create a class for each one of your cases that inherits from a common interface (let's call it ICommon) that exposes a common method for each case (in your case a Create method) and then inject that interface in the constructor of ServiceClass.

Then when you want to use ServiceClass, you will have to provide an actual implementation of ICommon (one of the classes you extracted from each case) and finally you only have to call entity.Create.

I believe this is the strategy pattern, that in summary says that you should extract an algorithm in a different class under a common interface.

Finally, this refactoring will reduce the cyclotomic complexity of your code (this mainly means that you reduce the branching on your code) which always a good thing.

Answer 3

Use a Dictionary. Something like this:

Dictionary<int, ServiceClass> dictionary = new Dictionary<int, ServiceClass>()
{
    {1,  new ServiceClass()},
    {2,  new ServiceClass()},
    {3,  new BTWithdrawal()},//assume BTWithdrawal inherits from ServiceClass
};

An example of how using it:

ServiceClass value=new ServiceClass();
value.FromServiceId=1;
value.ToServiceId = 2;
dictionary.TryGetValue(value.FromServiceId, out value);
//or dictionary.TryGetValue(value.ToServiceId, out value);
if (value != null) MessageBox.Show(value.Id.ToString());

Answer 4

What you could do is to put all the variations into an enum and call the enum values exactly like your methods that you would like to call. (I would suggest not to use numbers in the name, since the compiler won't allow it)

For the sake of simplicity and testability I put the enum and the methods into the same class:

public class ServiceClass
{
    public enum ServiceID
    {
        OneKWithdrawal,
        Ten_KWithdrawal,
        BTWithdrawal,
        OneKDeposit,
        Ten_KDeposit,
        BTDeposit
    }
    public ServiceID From_Ser_ID { get; set; }
    public ServiceID To_Ser_ID { get; set; }

    public void One_KWithdrawal()
    { Console.WriteLine("One_KWithdrawal"); }

    public void Ten_KWithdrawal()
    { Console.WriteLine("Ten_KWithdrawal"); }

    public void BTWithdrawal()
    { Console.WriteLine("BTWithdrawal"); }

    public void One_KDeposit()
    { Console.WriteLine("One_KDeposit"); }

    public void Ten_KDeposit()
    { Console.WriteLine("Ten_KDeposit"); }
}

This would be the method that would execute your if-condition methods. It uses reflection to access the methods that are coded in the enum. You probably have to adjust the object parameter in the Invoke(sc, null); call depending on where your methods are situated. If they are in the same class as where you would call execute you can use this.

public static void execute(ServiceClass sc)
{
    sc.GetType().GetMethod(sc.From_Ser_ID.ToString()).Invoke(sc, null);
    sc.GetType().GetMethod(sc.To_Ser_ID.ToString()).Invoke(sc, null);
}

And here you can test the entire code:

public static void Main(string[] args)
{

    ServiceClass entity = new ServiceClass();
    entity.From_Ser_ID = ServiceClass.ServiceID.BTWithdrawal;
    entity.To_Ser_ID = ServiceClass.ServiceID.Ten_KDeposit;

    execute(entity);
}

So you would end up with an enum and 2 lines of code.