Refactoring - replace Switch statement with state/strategy
Switch statements is procedural structure, not object programming, it can be replaced by strategy pattern with implementation of interface/abstract strategy, with concrete strategies.
public class SwitchToReplace
{
public static void Main()
{
Console.WriteLine(Get(Instruments.Telephone));
Console.WriteLine(Get(Instruments.Mobile));
Console.WriteLine(Get(Instruments.Television));
Console.WriteLine(Get(Instruments.Guitar));
Console.ReadLine();
}
public enum Instruments
{
Telephone,
Mobile,
Television,
Guitar
}
public static string Get(Instruments instruments)
{
string value;
switch (instruments)
{
case Instruments.Telephone:
Console.WriteLine("Case 1");
value = "Telephone";
break;
case Instruments.Mobile:
Console.WriteLine("Case 2");
value = "Mobile";
break;
case Instruments.Television:
Console.WriteLine("Case 3");
value = "Television";
break;
default:
Console.WriteLine("Default case");
value = "Default case";
break;
}
return value;
}
}
Replace Switch statement with State/Strategy pattern
public class SwitchReplaced
{
public enum InstrumentEnum
{
Telephone,
Mobile,
Television,
Guitar
}
//define an abstract class and its method signature
public abstract class Instrument
{
public abstract string GetInstrumentName();
}
//inherit abstract class and override it's method
public class InstrumentTelephone : Instrument
{
public override string GetInstrumentName()
{
Console.WriteLine("Case 1");
return "Telephone";
}
}
public class InstrumentMobile : Instrument
{
public override string GetInstrumentName()
{
Console.WriteLine("Case 2");
return "Mobile";
}
}
public class InstrumentTelevision : Instrument
{
public override string GetInstrumentName()
{
Console.WriteLine("Case 3");
return "Television";
}
}
public class InstrumentGuitar : Instrument
{
public override string GetInstrumentName()
{
Console.WriteLine("Case 4");
return "Guitar";
}
}
public class InstrumentContext
{
private readonly Instrument _instrumentInstance;
//put abstract class Instrument's instance in constructor, assign it to local variable
public InstrumentContext(Instrument instrument)
{
_instrumentInstance = instrument;
}
//Invoke method of concrete strategy
public string InvokeGetInstrumentName()
{
return _instrumentInstance.GetInstrumentName();
}
}
//Extract same calling code in a single method
public string InstrumentInfo(Instrument instrument)
{
InstrumentContext context = new InstrumentContext(instrument);
return context.InvokeGetInstrumentName();
}
public static void Main()
{
SwitchReplaced sr = new SwitchReplaced();
//call
Console.WriteLine(sr.InstrumentInfo(new InstrumentGuitar()));
Console.WriteLine(sr.InstrumentInfo(new InstrumentMobile()));
Console.ReadLine();
}
}
I hope this post can do help to you! enjoy coding!
