Design Patterns
Example 2: Logistics System
In a logistics system, you might need to create different types of transport objects such as trucks, ships, and airplanes. Using the Factory Pattern, you can create a transport factory that generates the appropriate transport type based on the input.
Step 1: Define an interface for transport.
public interface ITransport
{
void Deliver();
}
Step 2: Implement concrete classes for each transport type.
public class Truck : ITransport
{
public void Deliver()
{
Console.WriteLine("Delivering by land in a truck.");
}
}
public class Ship : ITransport
{
public void Deliver()
{
Console.WriteLine("Delivering by sea in a ship.");
}
}
public class Airplane : ITransport
{
public void Deliver()
{
Console.WriteLine("Delivering by air in an airplane.");
}
}
Step 3: Create a Factory class to generate the appropriate transport object.
public class TransportFactory
{
public ITransport CreateTransport(string type)
{
if (string.IsNullOrEmpty(type))
{
return null;
}
switch (type.ToUpper())
{
case "TRUCK":
return new Truck();
case "SHIP":
return new Ship();
case "AIRPLANE":
return new Airplane();
default:
return null;
}
}
}
Step 4: Use the Factory in the client code.
class Program
{
static void Main(string[] args)
{
TransportFactory factory = new TransportFactory();
ITransport transport = factory.CreateTransport("TRUCK");
transport?.Deliver();
transport = factory.CreateTransport("SHIP");
transport?.Deliver();
transport = factory.CreateTransport("AIRPLANE");
transport?.Deliver();
}
}
General Tips!
- Identify Common Problems: Recognize recurring problems in your code to determine which design pattern can provide a solution.
- Understand the Principles: Familiarize yourself with SOLID principles as they often align with the motivations behind design patterns.
- Use Patterns Judiciously: Avoid overusing patterns; apply them only when they provide a clear benefit.
- Learn by Example: Study real-world examples of design patterns to see how they are implemented in practice.
- Refactor When Necessary: Don’t force a pattern from the start; refactor your code to introduce patterns when a need becomes apparent.
- Stay Flexible: Patterns are guidelines, not strict rules. Adapt them to fit your specific context.
- Document Your Design: Clearly document the use of design patterns to help future maintainers understand your design decisions.