CODESAMPLE

Adapter - Dart

Adapter Dart

The Adapter pattern converts the interface of a class into another interface clients expect. It lets classes work together that couldn’t otherwise because of incompatible interfaces. In this Dart example, we have a LegacyPrinter with a printLegacy() method and a ModernPrinter interface expecting printModern(). The PrinterAdapter adapts the LegacyPrinter to fulfill the ModernPrinter interface, enabling a ModernPrintingService to work with it. This follows Dart’s use of interfaces (implemented by implements) and class composition to achieve adaptation.

// The target interface that clients can work with.
abstract class ModernPrinter {
  void printModern(String text);
}

// The legacy class with an incompatible interface.
class LegacyPrinter {
  void printLegacy(String text) {
    print('Legacy Printer: Printing - $text');
  }
}

// The adapter class that makes the legacy class compatible.
class PrinterAdapter implements ModernPrinter {
  final LegacyPrinter legacyPrinter;

  PrinterAdapter(this.legacyPrinter);

  @override
  void printModern(String text) {
    legacyPrinter.printLegacy(text);
  }
}

// Client code that uses the modern interface
class ModernPrintingService {
  void printDocument(ModernPrinter printer, String document) {
    print('Modern Printing Service: Preparing document...');
    printer.printModern(document);
    print('Modern Printing Service: Document printed.');
  }
}

void main() {
  final legacyPrinter = LegacyPrinter();
  final adapter = PrinterAdapter(legacyPrinter);
  final printingService = ModernPrintingService();

  printingService.printDocument(adapter, 'Hello, Adapted World!');
}