Context and Problem
Managing relationships between large numbers of objects and components can make a system difficult to understand and maintain.
- Complex relationships between objects or components.
- Difficulty in reusing parts of the system due to tightly coupled components.
- Difficult to scale the system as the number of components grows.
- Maintenance overhead as more components are added to the system.
Solution
Structural patterns help simplify the relationships and dependencies between objects and components by providing reusable solutions for organizing system structure.
- Analyze how components or objects are related and how they interact.
- Use patterns like Adapter, Composite, Decorator, Facade, Flyweight, and Proxy to restructure relationships between objects.
- Enable reuse and maintainability by promoting separation of concerns and encapsulating complex interactions in simpler components.
- Enhance scalability by ensuring that the system components can be easily extended or substituted.
Benefits
- Reusability
- Encourages object reuse by simplifying relationships between components and objects.
- Maintainability
- By simplifying the system structure, these patterns make it easier to maintain and extend the system.
- Flexibility
- Structural patterns make it easier to adapt the system to changing requirements or to add new features.
- Scalability
- Structural patterns enable the system to scale more easily as new components or features are added.
Trade-offs
- Increased Indirection
- Structural patterns, especially Proxy and Adapter, can introduce an extra layer of indirection, which may complicate debugging.
- Additional Complexity
- Some patterns, such as Composite, may lead to an increase in the number of objects or classes.
- Performance Overhead
- Some patterns, like Proxy, may introduce additional overhead due to extra layers between the client and the actual object.
Issues and Considerations
- Misapplication of Patterns
- Structural patterns should be applied when there is a need to simplify the structure and interactions of objects, but misapplying them can lead to unnecessary complexity.
- Maintenance of Layers
- Managing layers of abstractions in patterns like Decorator or Proxy can become challenging over time.
When to Use This Pattern
- When you need to simplify complex relationships between components or classes.
- When you want to decouple client and implementation, making the system easier to modify.
- When you need to scale a system by introducing new components or classes without breaking the existing system.
- When you need to add new functionality to objects dynamically and flexibly.