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How can you use the strategy pattern instead of conditional logic in code?

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Conditional logic is a common way of implementing different behaviors based on some conditions or inputs. However, it can also lead to code that is hard to read, maintain, and test, especially when the number of conditions or behaviors increases. In this article, you will learn how you can use the strategy pattern, a popular object-oriented design pattern, to replace conditional logic with polymorphism and make your code more flexible and extensible.

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Gaurav Arora

SDE-2 DigitalOcean | 3 X INSTA AWARD WINNER AT HT | Meta Hackercup AIR-51 2022 | System Design and DSA ??
Vasil Dakov

PHP consultant, developer and architect
Vlad Khrapski

Building RevOps solutions in Salesforce for mid-size IT companies | Solution Architect - Tech Lead - Consultant

1 What is the strategy pattern?

The strategy pattern is a behavioral design pattern that defines a family of algorithms or strategies, encapsulates each one in a separate class, and makes them interchangeable at runtime. The strategy pattern allows you to vary the behavior of an object without changing its class or modifying its structure. The strategy pattern consists of three main components: a context, a strategy interface, and concrete strategy classes.

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Vasil Dakov

PHP consultant, developer and architect
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In my recent project at work, I found a perfect opportunity to leverage the Strategy Pattern to enhance the flexibility and maintainability of our codebase. The project involved implementing a complex pricing engine for an e-commerce platform, where different pricing algorithms could be applied based on various factors such as customer type, product category, and promotions.

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Vlad Khrapski

Building RevOps solutions in Salesforce for mid-size IT companies | Solution Architect - Tech Lead - Consultant
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In addition to the description, the strategy pattern helps you to avoid a long list of if/else statements by structuring when (context) and what (concrete strategy) should be executed.

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2 How does the strategy pattern work?

The context is the class that uses the strategy pattern to delegate some of its behavior to a strategy object. The context does not know the details of how the strategy implements the behavior, it only knows the strategy interface that defines a common method for all strategies. The context can have a reference to a strategy object as an attribute, a parameter, or a dependency injection. The context can also change the strategy object at runtime according to some criteria or user input.

The strategy interface is an abstract class or an interface that declares a method that all concrete strategies must implement. The method represents the behavior that the context delegates to the strategy object. The strategy interface ensures that the context and the concrete strategies are loosely coupled and can vary independently.

The concrete strategy classes are subclasses or implementations of the strategy interface that provide different versions of the behavior. The concrete strategies encapsulate the logic and data that are specific to each algorithm or strategy. The concrete strategies can be created and initialized by the context, by a factory, or by a client.

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Vlad Khrapski

Building RevOps solutions in Salesforce for mid-size IT companies | Solution Architect - Tech Lead - Consultant
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There are 3 main points: a context, a strategy interface, and concrete strategy classes. Example. I press the cappuccino button on my coffee machine in the morning. Context. I define the context (cappuccino) when I select a beverage on the screen. Interface. The interface of the coffee machine is the beverage making. Depending on the model, the list of beverages (context and corresponding strategies) may be different. Concrete strategy. The moment I press the cappuccino button, the coffee machine selects a program (a concrete strategy) for preparation.

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Amruta Jahagirdar

"Experienced .NET Architect | Masters in CS Georgia Tech USA| Author, Mentor, AI Enthusiast | Transforming Ideas into Innovative Solutions for 14 Years"
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Instead of using conditional logic to choose between different algorithms directly in your code, you delegate the algorithm selection to a separate class, known as the context, which contains a reference to the selected strategy. 1.Define the Strategy Interface 2.Implement Concrete Strategies 3.Create the Context Class 4.Inject Strategy Object 5.Invoke the Strategy

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3 Why use the strategy pattern instead of conditional logic?

Conditional logic is a simple and straightforward way of implementing different behaviors based on some conditions or inputs. For example, you can use a switch statement or a series of if-else statements to check the country and apply the corresponding formula for the shipping cost. However, this approach has some drawbacks that can affect the quality and maintainability of your code, such as making your code more complex and verbose, introducing duplication and inconsistency, reducing flexibility and extensibility, and making it harder to test. The strategy pattern can help you overcome these issues by replacing conditional logic with polymorphism. Polymorphism allows an object to behave differently depending on its type or state. With the strategy pattern, you define different behaviors as separate classes that implement a common interface. Then, you can use a reference to the interface to invoke the appropriate behavior at runtime without knowing or caring about the concrete implementation. This way, you can make your code simpler and more concise, eliminate duplication and inconsistency, increase flexibility and extensibility, and make it easier to test.

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Gaurav Arora

SDE-2 DigitalOcean | 3 X INSTA AWARD WINNER AT HT | Meta Hackercup AIR-51 2022 | System Design and DSA ??
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There are many good reasons to use strategy pattern, say in a class MusicPlayer there is a method getNextSong() , the behavior of this method is depends on what Mode(Enum) mode is Selected- RepeatSameSong, RepeatEntirePlayList, NoRepeat. So in this method you could either have a if-else cases and handle logic based on this Mode or the better way would be to separate this logic and use strategy pattern . In this way this part of code is loosely coupled so you can add new modes, change functionality of existing modes and you only need to test this particular strategy and not the entire class. Hence it reduces code duplication, makes the components loosely coupled which makes it flexible and easier to test.

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4 How to apply the strategy pattern in code?

To apply the strategy pattern in code, you need to identify the behavior that varies in your code and extract it into a separate method, define a strategy interface that declares the method signature for the behavior, create concrete strategy classes that implement the strategy interface and provide different versions of the behavior, create a context class that has a reference to a strategy object as an attribute, parameter or dependency injection, and assign the concrete strategy objects to the context object according to some criteria or user input. For example, if you have a class called Calculator that performs some arithmetic operations on two numbers, you can use the strategy pattern to define different operations as separate classes that implement a common interface. Then you can use a reference to the interface to invoke the appropriate operation at runtime without knowing or caring about the concrete implementation. By doing this, you can make your code less complex, verbose, and inflexible. Reporting and documenting the incident will also help inform and reassure stakeholders while providing valuable insights for improving your cloud security posture.

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5 What are some examples of the strategy pattern in real-world scenarios?

The strategy pattern is a widely used design pattern that can be applied to many real-world scenarios where you need to vary the behavior of an object based on some conditions or inputs. For instance, it can be used for sorting algorithms, payment methods, and compression algorithms. With sorting algorithms, you can define different sorting algorithms as separate classes that implement a common interface and use a reference to the interface to sort an array or collection of elements at runtime. Similarly, you can use the strategy pattern to define different payment methods and compression algorithms as separate classes that implement a common interface and invoke the appropriate method or algorithm at runtime depending on the user preference or availability of the method.

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Vlad Khrapski

Building RevOps solutions in Salesforce for mid-size IT companies | Solution Architect - Tech Lead - Consultant
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One of my recent examples is related with payments. We had requirements to support multiple payment methods: card payments only at first, bank transfers in the next phase. Initial design: - The payment methods can be configured. - The payment component shows the available payment methods. - When you click on a payment button, the component selects the strategy corresponding to the selected method.

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6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

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How can you use the strategy pattern instead of conditional logic in code?

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1 What is the strategy pattern?

2 How does the strategy pattern work?

3 Why use the strategy pattern instead of conditional logic?

4 How to apply the strategy pattern in code?

5 What are some examples of the strategy pattern in real-world scenarios?

6 Here’s what else to consider

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