When is the Adapter Pattern Applicable?

1. Facilitating Collaboration Between Incompatible Interfaces

The primary use of the Adapter pattern is to enable interaction between objects that have incompatible interfaces. This situation often arises when an object is unsure of which method to invoke due to differing interfaces. The Adapter pattern addresses this challenge by providing an intermediary that conforms to the expected interface, thus simplifying usage. This intermediary, referred to as an adapter, conceals the complexities of the conversion process.

2. Integrating Components with Similar Functions

This pattern is also beneficial when two components with distinct interfaces yet similar functionalities need to work together. If their functionalities diverge, the Adapter pattern can modify, add, or remove behaviors, but it should not alter the fundamental purpose of the components. Its role is strictly to transform one interface into another, ensuring seamless communication between disparate systems.

3. Decoupling Implementation from Interface

The Adapter pattern is ideal for situations where unrelated interfaces must interact, especially when the needed interface may evolve over time. By utilizing an adapter, we can isolate implementation details from client code, thereby minimizing dependencies and safeguarding the code against changes in the API. The adapter serves as a translator between the current interface and the required one, allowing for modifications without necessitating changes to the client code. This approach enhances extensibility without compromising the existing implementation, aligning with the Open/Closed Principle.

Section 1.1: Practical Example in Swift

To illustrate the Adapter pattern, let’s consider a brief example using Swift. Suppose we are developing an application that displays a list of individuals from a database. The API structure may look like this:

struct Person {

var name: String

var surname: String

var age: Int

var gender: String

}

However, we prefer not to utilize API models directly within our interface layer. Therefore, we need to create a decoupled UI layer:

protocol PersonUI {

var fullName: String { get }

var personAge: Int { get }

}

In this scenario, we will use an instance of PersonUI at the interface layer to act as a converter between the API layer and the UI layer. Thus, we have both an API model and a UI model (the converter) and need to convert the API model to the UI model. By conforming to the protocol, we can easily achieve this:

extension Person: PersonUI {

var fullName: String {

return name + " " + surname

}

var personAge: Int {

return age

}

}

Summary of the Adapter Pattern

The Adapter pattern serves as a structural design framework that integrates classes and objects into a larger system. It is particularly useful when objects with incompatible interfaces need to collaborate. By transforming one interface into another, the Adapter pattern facilitates communication and reduces dependencies while enhancing client extensibility without modification.