This document discusses structural design patterns including the adapter, composite, and decorator patterns. It provides definitions and benefits of structural patterns, describes how to implement the adapter, composite, and decorator patterns through code examples, and lists resources for additional information on design patterns.

1. CODE LIKE A NINJA
STRUCTURAL DESIGN PATTERNS

2. SESSION RESOURCES
• Presentation session notes including link to this session, will be
available on http://learningaboutfudge.blogspot.com
• All the source for this session is publically available at:
https://github.com/SheepWorx/Training
• RSS Feed:
http://learningaboutfudge.blogspot.com/feeds/posts/default?alt=rs
s
• Local Network: dmeyer-msharetrainingCode Like a Ninja
• Source was compiled using Visual Studio 2012
• http://www.gofpatterns.com/

3. Design Patterns
Creational Design Patterns
Structural Design Patterns
Behavioral Design Patterns

4. STRUCTURAL DESIGN PATTERNS
Definition
Structural design patterns are design patterns that ease the
design by identifying a simple way to realize relationships
between entities. Structural patterns are for tying together
existing function.

5. • Adapter
• Bridge
• Composite
• Decorator
• Façade
• Flyweight
• Proxy
STRUCTURAL DESIGN PATTERNS

6. ADAPTER PATTERN
• Acts as an intermediary between two classes
• Enables incompatible interfaces to work together
• Implements an interface known to its clients and provides
access to an instance of class not known to its clients

7. ADAPTER PATTERN

8. ADAPTER PATTERN – BENEFITS
• Allows two or more incompatible objects to communicate and
interact
• Improves reusability of older functionality

9. ADAPTER PATTERN – WHEN TO USE IT
• You want to use an existing class, and its interface does not match
the interface you need.
• You want to create a reusable class that cooperates with unrelated or
unforeseen classes, that is, classes that do not necessarily have
compatible interfaces.
• You want to use an object in an environment that expects an
interface that is different from the object's interface.
• Interface translation among multiple sources must occur.

10. ADAPTER PATTERN
See code example

11. COMPOSITE PATTERN
• Enables you to create hierarchical tree of varying complexity
Motivation
When dealing with Tree-structured data, programmers often
have to discriminate between a leaf-node and a branch. The
solution is an interface that allows treating complex and
primitive objects uniformly.

12. COMPOSITE PATTERN

13. COMPOSITE PATTERN – BENEFITS
• Defines class hierarchies consisting of primitive objects and
composite objects
• Makes it easier to add new kinds of components
• Provides flexibility of structure and a manageable interface

14. COMPOSITE PATTERN – WHEN TO USE IT
• You want to represent the whole hierarchy or part of the
hierarchy of objects.
• You want clients to be able to ignore the difference between
compositions of objects and individual objects.
• The structure can have any level of complexity, and is dynamic.

15. COMPOSITE PATTERN
See code example

16. DECORATOR PATTERN
• Enables you to add or remove functionality without changing
the external appearance or function of the object

17. DECORATOR PATTERN

18. DECORATOR PATTERN – BENEFITS
• More flexibility than static inheritance.
• Avoids feature-laden classes high up in the hierarchy
• Simplifies coding because you write a series of classes, each
targeted at a specific part of the functionality, rather than
coding all behaviour into the object
• Enhances the object's extensibility because you make changes
by coding new classes.

19. DECORATOR PATTERN – WHEN TO USE IT
• You want to add responsibilities to individual objects
dynamically and transparently, that is without affecting other
objects
• You want to add responsibilities to the object that you want to
change in the future
• When extension by static sub-classing is impractical.

20. DECORATOR PATTERN
See code example

21. SESSION RESOURCES
• Presentation session notes including link to this session, will be
available on http://learningaboutfudge.blogspot.com
• All the source for this session is publically available at:
https://github.com/SheepWorx/Training
• RSS Feed:
http://learningaboutfudge.blogspot.com/feeds/posts/default?alt=rs
s
• Local Network: dmeyer-msharetrainingCode Like a Ninja
• Source was compiled using Visual Studio 2012
• http://www.gofpatterns.com/