Apply discount changes with Strategy pattern

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I am implementing strategy pattern. I have defined a strategy as interfaces and concrete classes to implement the strategy. Based on user selection/configuration, the algorithm to apply the discount changes.

 public interface IStrategy
 
 double calculate(double x, double y);

concrete classes implementing the gold strategy is listed below -

public class clsGoldDiscountStrategy : IStrategy
 
 public double calculate(double x, double y)
 
 return (x * y) * 0.8;
 
 
}

concrete classes implementing the platinumstrategy is listed below -

public class clsPlatinumDiscountStrategy : IStrategy
 
 public double calculate(double x, double y)
 
 return (x * y) * 0.7;

The business logic to apply

public class clsBL
 
 public double costPrice get; set; 
 public double qty get; set; 
 IStrategy _strategy;

 public clsBL(IStrategy strategy)
 
 _strategy = strategy;
 

 public double GetfinalPrice(double cp, double qty)
 
 return _strategy.calculate(cp, qty);

//Main method

static void Main(string args)
 
 Console.WriteLine("Enter the discount Plan (Gold/Platinum)");
 string filter = Console.ReadLine().ToUpper();
 double result = 0;

 if (filter.Length > 0)
 
 switch (filter)
 
 case "GOLD":
 //Gold 
 clsBL blgold = new clsBL(new clsGoldDiscountStrategy());
 blgold.costPrice = 5;
 blgold.qty = 10;

 result = blgold.GetfinalPrice(blgold.costPrice, blgold.qty);
 break;

 case "PLATINUM":
 //Platinum
 clsBL blplatinum = new clsBL(new clsPlatinumDiscountStrategy());
 blplatinum.costPrice = 10;
 blplatinum.qty = 8;

 result = blplatinum.GetfinalPrice(blplatinum.costPrice, blplatinum.qty);
 break;
 default:
 Console.WriteLine("Enter the discount value as either gold or platinum");
 break;
 

 Console.WriteLine("The result for " + filter + " is " + result);

 
 else
 
 Console.WriteLine("Enter the discount value");
 return;
 


 Console.ReadLine();

edited 3 hours ago

t3chb0t

32.4k64299

asked 7 hours ago

krishna_v

1161

migrated from stackoverflow.com 3 hours ago

This question came from our site for professional and enthusiast programmers.

add a commentÂ |Â

up vote
3
down vote

favorite

 public interface IStrategy
 
 double calculate(double x, double y);

concrete classes implementing the gold strategy is listed below -

public class clsGoldDiscountStrategy : IStrategy
 
 public double calculate(double x, double y)
 
 return (x * y) * 0.8;
 
 
}

concrete classes implementing the platinumstrategy is listed below -

public class clsPlatinumDiscountStrategy : IStrategy
 
 public double calculate(double x, double y)
 
 return (x * y) * 0.7;

The business logic to apply

public class clsBL
 
 public double costPrice get; set; 
 public double qty get; set; 
 IStrategy _strategy;

 public clsBL(IStrategy strategy)
 
 _strategy = strategy;
 

 public double GetfinalPrice(double cp, double qty)
 
 return _strategy.calculate(cp, qty);

//Main method

static void Main(string args)
 
 Console.WriteLine("Enter the discount Plan (Gold/Platinum)");
 string filter = Console.ReadLine().ToUpper();
 double result = 0;

 if (filter.Length > 0)
 
 switch (filter)
 
 case "GOLD":
 //Gold 
 clsBL blgold = new clsBL(new clsGoldDiscountStrategy());
 blgold.costPrice = 5;
 blgold.qty = 10;

 result = blgold.GetfinalPrice(blgold.costPrice, blgold.qty);
 break;

 case "PLATINUM":
 //Platinum
 clsBL blplatinum = new clsBL(new clsPlatinumDiscountStrategy());
 blplatinum.costPrice = 10;
 blplatinum.qty = 8;

 result = blplatinum.GetfinalPrice(blplatinum.costPrice, blplatinum.qty);
 break;
 default:
 Console.WriteLine("Enter the discount value as either gold or platinum");
 break;
 

 Console.WriteLine("The result for " + filter + " is " + result);

 
 else
 
 Console.WriteLine("Enter the discount value");
 return;
 


 Console.ReadLine();

edited 3 hours ago

t3chb0t

32.4k64299

asked 7 hours ago

krishna_v

1161

migrated from stackoverflow.com 3 hours ago

This question came from our site for professional and enthusiast programmers.

add a commentÂ |Â

up vote
3
down vote

favorite

 public interface IStrategy
 
 double calculate(double x, double y);

concrete classes implementing the gold strategy is listed below -

public class clsGoldDiscountStrategy : IStrategy
 
 public double calculate(double x, double y)
 
 return (x * y) * 0.8;
 
 
}

concrete classes implementing the platinumstrategy is listed below -

public class clsPlatinumDiscountStrategy : IStrategy
 
 public double calculate(double x, double y)
 
 return (x * y) * 0.7;

The business logic to apply

public class clsBL
 
 public double costPrice get; set; 
 public double qty get; set; 
 IStrategy _strategy;

 public clsBL(IStrategy strategy)
 
 _strategy = strategy;
 

 public double GetfinalPrice(double cp, double qty)
 
 return _strategy.calculate(cp, qty);

//Main method

static void Main(string args)
 
 Console.WriteLine("Enter the discount Plan (Gold/Platinum)");
 string filter = Console.ReadLine().ToUpper();
 double result = 0;

 if (filter.Length > 0)
 
 switch (filter)
 
 case "GOLD":
 //Gold 
 clsBL blgold = new clsBL(new clsGoldDiscountStrategy());
 blgold.costPrice = 5;
 blgold.qty = 10;

 result = blgold.GetfinalPrice(blgold.costPrice, blgold.qty);
 break;

 case "PLATINUM":
 //Platinum
 clsBL blplatinum = new clsBL(new clsPlatinumDiscountStrategy());
 blplatinum.costPrice = 10;
 blplatinum.qty = 8;

 result = blplatinum.GetfinalPrice(blplatinum.costPrice, blplatinum.qty);
 break;
 default:
 Console.WriteLine("Enter the discount value as either gold or platinum");
 break;
 

 Console.WriteLine("The result for " + filter + " is " + result);

 
 else
 
 Console.WriteLine("Enter the discount value");
 return;
 


 Console.ReadLine();

edited 3 hours ago

t3chb0t

32.4k64299

asked 7 hours ago

krishna_v

1161

 public interface IStrategy
 
 double calculate(double x, double y);

concrete classes implementing the gold strategy is listed below -

public class clsGoldDiscountStrategy : IStrategy
 
 public double calculate(double x, double y)
 
 return (x * y) * 0.8;
 
 
}

concrete classes implementing the platinumstrategy is listed below -

public class clsPlatinumDiscountStrategy : IStrategy
 
 public double calculate(double x, double y)
 
 return (x * y) * 0.7;

The business logic to apply

public class clsBL
 
 public double costPrice get; set; 
 public double qty get; set; 
 IStrategy _strategy;

 public clsBL(IStrategy strategy)
 
 _strategy = strategy;
 

 public double GetfinalPrice(double cp, double qty)
 
 return _strategy.calculate(cp, qty);

//Main method

static void Main(string args)
 
 Console.WriteLine("Enter the discount Plan (Gold/Platinum)");
 string filter = Console.ReadLine().ToUpper();
 double result = 0;

 if (filter.Length > 0)
 
 switch (filter)
 
 case "GOLD":
 //Gold 
 clsBL blgold = new clsBL(new clsGoldDiscountStrategy());
 blgold.costPrice = 5;
 blgold.qty = 10;

 result = blgold.GetfinalPrice(blgold.costPrice, blgold.qty);
 break;

 case "PLATINUM":
 //Platinum
 clsBL blplatinum = new clsBL(new clsPlatinumDiscountStrategy());
 blplatinum.costPrice = 10;
 blplatinum.qty = 8;

 result = blplatinum.GetfinalPrice(blplatinum.costPrice, blplatinum.qty);
 break;
 default:
 Console.WriteLine("Enter the discount value as either gold or platinum");
 break;
 

 Console.WriteLine("The result for " + filter + " is " + result);

 
 else
 
 Console.WriteLine("Enter the discount value");
 return;
 


 Console.ReadLine();

c# design-patterns

edited 3 hours ago

t3chb0t

32.4k64299

asked 7 hours ago

krishna_v

1161

edited 3 hours ago

t3chb0t

32.4k64299

asked 7 hours ago

krishna_v

1161

edited 3 hours ago

t3chb0t

32.4k64299

edited 3 hours ago

t3chb0t

32.4k64299

edited 3 hours ago

t3chb0t

32.4k64299

asked 7 hours ago

krishna_v

1161

asked 7 hours ago

krishna_v

1161

asked 7 hours ago

krishna_v

1161

migrated from stackoverflow.com 3 hours ago

This question came from our site for professional and enthusiast programmers.

migrated from stackoverflow.com 3 hours ago

This question came from our site for professional and enthusiast programmers.

add a commentÂ |Â

2 Answers
2

active

oldest

votes

up vote
2
down vote

The classes seem OK but the usage makes no sense:

 case "GOLD":
 //Gold 
 clsBL blgold = new clsBL(new clsGoldDiscountStrategy());
 blgold.costPrice = 5;
 blgold.qty = 10;

 result = blgold.GetfinalPrice(blgold.costPrice, blgold.qty);
 break;

This code (and the other switch case) does not use the polymorphism that the interface IStrategy enables. Rather, you can have simply written this code as:

 case "GOLD":
 double GetGoldPrice(double x, double y) => (x * y) * 0.8;
 result = GetGoldPrice(5, 10);
 break;

Here, all classes and interfaces are deleted. There is just a static method.

If you want to use the strategy pattern it must look something like:

IStrategy strategy = GetStrategy();
strategy.Calculate(...);

Here, GetStrategy() can return any object compliant with that interface and further code does depend on any concrete type.

Regarding naming, the classes do not have to be called "Strategy". I'd use the names IDiscountCalculator and GoldDicountCalculator. Or, instead of "Calculator" you could use "Model" or "Provider".

edited 3 hours ago

answered 4 hours ago

usr

635310

how do we pass the parameters in this?(for cost price and qty). you mean to say we do not add dependency injection to the clBL class. could you kindly detail me
â€“Â krishna_v
3 hours ago

I depends on the way you want the parameters to behave. Maybe you should give the parameters to the strategy constructor. Then, the parameters are fixed for the lifetime of the strategy object. If the parameters are dynamic, then they should be parameters to the Calculate method. They should not be fields of settable properties on IStrategy.
â€“Â usr
2 hours ago

Well, they could be settable if you want a strategy to be changeable. Nothing wrong with that in principle... But immutable objects usually make for a cleaner API.
â€“Â usr
2 hours ago

add a commentÂ |Â

up vote
0
down vote

x and y are really bad parameter names. I had to look at the client code to figure out that these were actually cost and quantity.

answered 8 mins ago

RubberDuck

27k454155

add a commentÂ |Â

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

up vote
2
down vote

The classes seem OK but the usage makes no sense:

 case "GOLD":
 //Gold 
 clsBL blgold = new clsBL(new clsGoldDiscountStrategy());
 blgold.costPrice = 5;
 blgold.qty = 10;

 result = blgold.GetfinalPrice(blgold.costPrice, blgold.qty);
 break;

This code (and the other switch case) does not use the polymorphism that the interface IStrategy enables. Rather, you can have simply written this code as:

 case "GOLD":
 double GetGoldPrice(double x, double y) => (x * y) * 0.8;
 result = GetGoldPrice(5, 10);
 break;

Here, all classes and interfaces are deleted. There is just a static method.

If you want to use the strategy pattern it must look something like:

IStrategy strategy = GetStrategy();
strategy.Calculate(...);

Here, GetStrategy() can return any object compliant with that interface and further code does depend on any concrete type.

edited 3 hours ago

answered 4 hours ago

usr

635310

how do we pass the parameters in this?(for cost price and qty). you mean to say we do not add dependency injection to the clBL class. could you kindly detail me
â€“Â krishna_v
3 hours ago

I depends on the way you want the parameters to behave. Maybe you should give the parameters to the strategy constructor. Then, the parameters are fixed for the lifetime of the strategy object. If the parameters are dynamic, then they should be parameters to the Calculate method. They should not be fields of settable properties on IStrategy.
â€“Â usr
2 hours ago

Well, they could be settable if you want a strategy to be changeable. Nothing wrong with that in principle... But immutable objects usually make for a cleaner API.
â€“Â usr
2 hours ago

add a commentÂ |Â

up vote
2
down vote

The classes seem OK but the usage makes no sense:

 case "GOLD":
 //Gold 
 clsBL blgold = new clsBL(new clsGoldDiscountStrategy());
 blgold.costPrice = 5;
 blgold.qty = 10;

 result = blgold.GetfinalPrice(blgold.costPrice, blgold.qty);
 break;

This code (and the other switch case) does not use the polymorphism that the interface IStrategy enables. Rather, you can have simply written this code as:

 case "GOLD":
 double GetGoldPrice(double x, double y) => (x * y) * 0.8;
 result = GetGoldPrice(5, 10);
 break;

Here, all classes and interfaces are deleted. There is just a static method.

If you want to use the strategy pattern it must look something like:

IStrategy strategy = GetStrategy();
strategy.Calculate(...);

Here, GetStrategy() can return any object compliant with that interface and further code does depend on any concrete type.

edited 3 hours ago

answered 4 hours ago

usr

635310

how do we pass the parameters in this?(for cost price and qty). you mean to say we do not add dependency injection to the clBL class. could you kindly detail me
â€“Â krishna_v
3 hours ago

I depends on the way you want the parameters to behave. Maybe you should give the parameters to the strategy constructor. Then, the parameters are fixed for the lifetime of the strategy object. If the parameters are dynamic, then they should be parameters to the Calculate method. They should not be fields of settable properties on IStrategy.
â€“Â usr
2 hours ago

Well, they could be settable if you want a strategy to be changeable. Nothing wrong with that in principle... But immutable objects usually make for a cleaner API.
â€“Â usr
2 hours ago

add a commentÂ |Â

up vote
2
down vote

The classes seem OK but the usage makes no sense:

 case "GOLD":
 //Gold 
 clsBL blgold = new clsBL(new clsGoldDiscountStrategy());
 blgold.costPrice = 5;
 blgold.qty = 10;

 result = blgold.GetfinalPrice(blgold.costPrice, blgold.qty);
 break;

This code (and the other switch case) does not use the polymorphism that the interface IStrategy enables. Rather, you can have simply written this code as:

 case "GOLD":
 double GetGoldPrice(double x, double y) => (x * y) * 0.8;
 result = GetGoldPrice(5, 10);
 break;

Here, all classes and interfaces are deleted. There is just a static method.

If you want to use the strategy pattern it must look something like:

IStrategy strategy = GetStrategy();
strategy.Calculate(...);

Here, GetStrategy() can return any object compliant with that interface and further code does depend on any concrete type.

edited 3 hours ago

answered 4 hours ago

usr

635310

The classes seem OK but the usage makes no sense:

 case "GOLD":
 //Gold 
 clsBL blgold = new clsBL(new clsGoldDiscountStrategy());
 blgold.costPrice = 5;
 blgold.qty = 10;

 result = blgold.GetfinalPrice(blgold.costPrice, blgold.qty);
 break;

This code (and the other switch case) does not use the polymorphism that the interface IStrategy enables. Rather, you can have simply written this code as:

 case "GOLD":
 double GetGoldPrice(double x, double y) => (x * y) * 0.8;
 result = GetGoldPrice(5, 10);
 break;

Here, all classes and interfaces are deleted. There is just a static method.

If you want to use the strategy pattern it must look something like:

IStrategy strategy = GetStrategy();
strategy.Calculate(...);

Here, GetStrategy() can return any object compliant with that interface and further code does depend on any concrete type.

edited 3 hours ago

answered 4 hours ago

usr

635310

edited 3 hours ago

answered 4 hours ago

usr

635310

answered 4 hours ago

usr

635310

answered 4 hours ago

usr

635310

how do we pass the parameters in this?(for cost price and qty). you mean to say we do not add dependency injection to the clBL class. could you kindly detail me
â€“Â krishna_v
3 hours ago

I depends on the way you want the parameters to behave. Maybe you should give the parameters to the strategy constructor. Then, the parameters are fixed for the lifetime of the strategy object. If the parameters are dynamic, then they should be parameters to the Calculate method. They should not be fields of settable properties on IStrategy.
â€“Â usr
2 hours ago

Well, they could be settable if you want a strategy to be changeable. Nothing wrong with that in principle... But immutable objects usually make for a cleaner API.
â€“Â usr
2 hours ago

add a commentÂ |Â

how do we pass the parameters in this?(for cost price and qty). you mean to say we do not add dependency injection to the clBL class. could you kindly detail me
â€“Â krishna_v
3 hours ago

I depends on the way you want the parameters to behave. Maybe you should give the parameters to the strategy constructor. Then, the parameters are fixed for the lifetime of the strategy object. If the parameters are dynamic, then they should be parameters to the Calculate method. They should not be fields of settable properties on IStrategy.
â€“Â usr
2 hours ago

Well, they could be settable if you want a strategy to be changeable. Nothing wrong with that in principle... But immutable objects usually make for a cleaner API.
â€“Â usr
2 hours ago

how do we pass the parameters in this?(for cost price and qty). you mean to say we do not add dependency injection to the clBL class. could you kindly detail me
â€“Â krishna_v
3 hours ago

I depends on the way you want the parameters to behave. Maybe you should give the parameters to the strategy constructor. Then, the parameters are fixed for the lifetime of the strategy object. If the parameters are dynamic, then they should be parameters to the Calculate method. They should not be fields of settable properties on IStrategy.
â€“Â usr
2 hours ago

Well, they could be settable if you want a strategy to be changeable. Nothing wrong with that in principle... But immutable objects usually make for a cleaner API.
â€“Â usr
2 hours ago

add a commentÂ |Â

up vote
0
down vote

x and y are really bad parameter names. I had to look at the client code to figure out that these were actually cost and quantity.

answered 8 mins ago

RubberDuck

27k454155

add a commentÂ |Â

up vote
0
down vote

x and y are really bad parameter names. I had to look at the client code to figure out that these were actually cost and quantity.

answered 8 mins ago

RubberDuck

27k454155

add a commentÂ |Â

up vote
0
down vote

x and y are really bad parameter names. I had to look at the client code to figure out that these were actually cost and quantity.

answered 8 mins ago

RubberDuck

27k454155

x and y are really bad parameter names. I had to look at the client code to figure out that these were actually cost and quantity.

answered 8 mins ago

RubberDuck

27k454155

answered 8 mins ago

RubberDuck

27k454155

answered 8 mins ago

RubberDuck

27k454155

answered 8 mins ago

RubberDuck

27k454155

add a commentÂ |Â

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