adapter design pattern

what is adapter pattern

• The adapter pattern allows classes that have different interfaces (properties/methods of an object) to work together. It translates the interface for a class to make it compatible with another class.
• This pattern is useful if an API is modified or new implementations are added to it. In this case, if the other parts of a system are still using the old API, the adapter pattern will translate the interface so that the two can work together.
• In plain words

Adapter pattern lets you wrap an otherwise incompatible object in an adapter to make it compatible with another class.

• Wikipedia says

In software engineering, the adapter pattern is a software design pattern that allows the interface of an existing class to be used as another interface. It is often used to make existing classes work with others without modifying their source code.

/**
 * The Target defines the domain-specific interface used by the client code.
 */
class Target {
    public request(): string {
        return 'Target: The default target\'s behavior.';
    }
}
 
/**
 * The Adaptee contains some useful behavior, but its interface is incompatible
 * with the existing client code. The Adaptee needs some adaptation before the
 * client code can use it.
 */
class Adaptee {
    public specificRequest(): string {
        return '.eetpadA eht fo roivaheb laicepS';
    }
}
 
/**
 * The Adapter makes the Adaptee's interface compatible with the Target's
 * interface.
 */
class Adapter extends Target {
    private adaptee: Adaptee;
 
    constructor(adaptee: Adaptee) {
        super();
        this.adaptee = adaptee;
    }
 
    public request(): string {
        const result = this.adaptee.specificRequest().split('').reverse().join('');
        return `Adapter: (TRANSLATED) ${result}`;
    }
}
 
/**
 * The client code supports all classes that follow the Target interface.
 */
function clientCode(target: Target) {
    console.log(target.request());
}
 
console.log('Client: I can work just fine with the Target objects:');
const target = new Target();
clientCode(target);
 
console.log('');
 
const adaptee = new Adaptee();
console.log('Client: The Adaptee class has a weird interface. See, I don\'t understand it:');
console.log(`Adaptee: ${adaptee.specificRequest()}`);
 
console.log('');
 
console.log('Client: But I can work with it via the Adapter:');
const adapter = new Adapter(adaptee);
clientCode(adapter);