Strategy pattern in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the Strategy pattern?

The Strategy pattern is a design pattern that lets you choose an algorithm's behavior at runtime. It defines a family of algorithms, puts each one in a separate class, and makes their objects interchangeable.

beginner

How does the Strategy pattern help in programming?

It helps by separating the algorithm from the code that uses it. This makes the code easier to change and extend without modifying existing code.

intermediate

In PHP, how do you implement the Strategy pattern?

You create an interface for the strategy, then create classes that implement this interface for each algorithm. The context class holds a reference to a strategy object and delegates work to it.

intermediate

What is the role of the Context class in the Strategy pattern?

The Context class uses a Strategy object to execute the algorithm. It does not know the details of the algorithm, only that it can call a method on the strategy.

beginner

Give a simple real-life example of the Strategy pattern.

Choosing a payment method in an online store is like the Strategy pattern. You can pay by credit card, PayPal, or bank transfer. Each payment method is a strategy, and the store uses the chosen one to process payment.

What does the Strategy pattern allow you to do?

A Create multiple unrelated classes

B Change the algorithm used at runtime

C Write code without any classes

D Avoid using interfaces

The Strategy pattern allows changing the algorithm at runtime by using different strategy objects.

In the Strategy pattern, what does the Context class do?

A Holds a reference to a strategy and uses it

B Implements all algorithms

C Defines the interface for strategies

D Creates new strategies dynamically

The Context class holds a strategy object and delegates work to it.

Which PHP feature is commonly used to define strategies?

A Interfaces

B Traits

C Abstract classes only

D Global functions

Interfaces define the contract that all strategy classes must follow.

Why is the Strategy pattern useful?

A It makes code run faster

B It forces all algorithms to be in one class

C It removes the need for classes

D It reduces code duplication and increases flexibility

The pattern helps reduce duplication and makes it easy to switch algorithms.

Which of these is NOT a benefit of the Strategy pattern?

A Easier to add new algorithms

B Better separation of concerns

C Harder to test individual algorithms

D Ability to change behavior at runtime

The Strategy pattern actually makes it easier to test algorithms separately.

Explain the Strategy pattern and how it separates concerns in code.

Think about how you can swap different ways to do something without changing the main code.

Describe a simple PHP example using the Strategy pattern for different sorting algorithms.

Imagine you want to sort data but want to pick the method later.