Adapter Desing Patter Under 1 minute - Software Desing Pattern

Real-World Analogy

Think of an electrical adapter for charging your phone while traveling abroad. The wall socket’s shape varies between countries, and your charger may not fit. Instead of buying a new charger, you use an adapter that connects your charger’s plug with the foreign socket. The adapter enables compatibility without altering the socket or the charger.

Example: Adapter Design Pattern in Software

Suppose you have existing code using an old printer (LegacyPrinter), but your new application expects a Printer interface with a different method signature.

Goal: Adapt LegacyPrinter so it can be used where Printer is expected.

from abc import ABC, abstractmethod

class Printer(ABC):
    @abstractmethod
    def print(self, message):
        pass

class LegacyPrinter:
    def print_document(self, text):
        print(f"LegacyPrinter prints: {text}")

class PrinterAdapter(Printer):
    def __init__(self, legacy_printer):
        self.legacy_printer = legacy_printer

    def print(self, message):
        # Translate the new interface call to the legacy method
        self.legacy_printer.print_document(message)

def client_code(printer: Printer):
    printer.print("Hello, Adapter Pattern!")

# Usage:
legacy = LegacyPrinter()
adapter = PrinterAdapter(legacy)

client_code(adapter)

Works well when you cannot change external libraries or legacy systems.

✅ Advantages:

• Allows integration with legacy code

• Promotes code reusability

• Keeps original code untouched

⚠️ Pitfalls:

• Too many adapters can clutter the design