1-adapter_pattern.md

Adapter Design Pattern in TypeScript

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What is the Adapter Pattern?

The Adapter Pattern allows incompatible interfaces to collaborate by providing a wrapper that translates requests from one interface to another.

It helps integrate existing classes or modules without modifying their original code.

Why and When to Use the Adapter Pattern?

Benefits:

• Compatibility: Lets incompatible interfaces work together.
• Reusability: Enables reuse of existing classes or components.
• Single Responsibility Principle: Keeps translation logic separate from business logic.

Use the Adapter Pattern when:

• You want to reuse existing code with an incompatible interface.
• Integrating legacy code or third-party libraries that don't match your interface.

Example of Adapter Pattern in TypeScript

Step 1: Existing Class with Incompatible Interface

class OldPrinter {
  oldPrint(text: string): void {
    console.log(`Old Printer printing: ${text}`);
  }
}

Step 2: Define Target Interface

interface Printer {
  print(text: string): void;
}

Step 3: Create Adapter Class

class PrinterAdapter implements Printer {
  private oldPrinter: OldPrinter;

  constructor(oldPrinter: OldPrinter) {
    this.oldPrinter = oldPrinter;
  }

  print(text: string): void {
    this.oldPrinter.oldPrint(text);
  }
}

Step 4: Using the Adapter

const oldPrinter = new OldPrinter();
const adapter: Printer = new PrinterAdapter(oldPrinter);

adapter.print("Hello, Adapter Pattern!");

Output

Old Printer printing: Hello, Adapter Pattern!

Conclusion

The Adapter Pattern bridges the gap between incompatible interfaces, enhancing compatibility and reuse of existing components without modifying their original implementations.