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Head First Design Patterns - PDF Free Download
downloads Views 1MB Size Report. DOWNLOAD PDF. 3 the DecoratorPattern g Decorating h Objects g I used to think real men subclassed everything. Download at blogger.com Praise for Head First Design Patterns “I received the book yesterday and started to read it Estimated Reading Time: 8 mins Head first java design patterns pdf free download. Page 1 HEAD FIRST: Design Patterns Eric Freeman Elisabeth Robson Bert Bates Kathy Sierra Beijing à ¢ â ¢ à ¢ â ¢ Boston Farnham à ¢ â ¢ à ¢ â ¢ Sebastopol Tokyo for the band of four, whose knowledge and experience in capturing e Communicating Design Patterns has changed the face of design software forever, and improved the life of Download Full Head First Design Patterns Book in PDF, EPUB, Mobi and All Ebook Format. You also can read online Head First Design Patterns and write the review about the book
Head first design patterns pdf download
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Start by pressing the button below! Home Add Document Sign In Register. Head First Design Patterns Home Head First Design Patterns. That was until I le Author: Elisabeth Freeman Eric Freeman Bert Bates Kathy Sierra, head first design patterns pdf download.
DOWNLOAD PDF. That was until I learned the power of extension at runtime, rather than at compile time. Now look at me! this is a new chapter 79 the starbuzz story Welcome to Starbuzz Coffee Starbuzz Coffee has made a name for itself as the fastest growing coffee shop around.
When they first went into business they designed their classes like this stract class, Beverage is an abbe verages subclassed by all ff ee shop. The getDescription method returns the description.
Beverage description The cost method is abstract; subclassses need to define their own implementation. DarkRoast HouseBlend cost cost Decaf cost Espresso cost Each subclass implements cost to return the cost of the beverage, head first design patterns pdf download. Starbuzz charges a head first design patterns pdf download for each of these, so they really need to get them built into their order system. What happens when the price of milk goes up? What do they do when they add a new caramel topping?
This is stupid; why do we need all these classes? Subclasses will still override costbut they will also invoke the super version so that they can calculate the total cost of the basic beverage plus the costs of the added condiments. e boolean These get and setndthiments. needs to compute Each cost methobedverage and then the cost of the ents by calling the add in the condim tation of cost. This is definitely the way to go. Sharpen your pencil What requirements or other factors might change that will impact this design?
Price changes for condiments will force us to alter existing code. New condiments will force us to add new methods and alter the cost method in the superclass. We may head first design patterns pdf download new beverages. For some of these beverages iced tea? What if a customer wants a double mocha? rn: Your tu 84 Chapter 3 aw in this is s e As w pter 1, idea! Cha ery bad av the decorator pattern Master and Student Master: Grasshopper, it has been some time since our last meeting.
Have you been deep in meditation on inheritance? Student: Yes, Master, head first design patterns pdf download. Master: Ah yes, you have made some progress. So, tell me my student, how then will you achieve reuse if not through inheritance? Master: Please, go on Student: When I inherit behavior by subclassing, that behavior is set statically at compile time.
In addition, all subclasses must inherit the same behavior. Master: Very good, Grasshopper, you are beginning to see the power of composition. Student: Yes, it is possible for me to add multiple new responsibilities to objects through this technique, including responsibilities that were not even thought of by the designer of the superclass.
Master: What have you learned about the effect of composition on maintaining your code? Student: Well, that is what I was getting at. By dynamically composing objects, I can add new functionality by writing new code rather than altering existing code. Master: Very good.
Enough for today, Grasshopper. I would like for you to go and meditate further on this topic Remember, head first design patterns pdf download, code should be closed to change like the lotus flower in the evening, yet open to extension like the lotus flower in the morning. you are here 4 85 the open-closed principle The Open-Closed Principle Grasshopper is on to one of the most important design principles: Design Principle Classes should be open for extension, but closed for modification.
Feel free to extend our classes with any new behavior you like. If your needs or requirements change and we know they willjust go ahead and make your own extensions. It must remain closed to modification. Our goal is to allow classes to be easily extended to incorporate new behavior without modifying existing code. What do we get if we accomplish this? Designs that are resilient to change and flexible enough to take on new functionality to meet changing requirements.
That sounds very contradictory. How can a design be both? It certainly sounds contradictory at first. After all, the less modifiable something is, the harder it is to extend, right? Think about the Observer Pattern in Chapter by adding new Observers, we can extend the Subject at any time, without adding code to head first design patterns pdf download Subject. Q: Okay, I understand Observable, but how do I generally design something to be extensible, yet closed for modification?
Making OO design flexible and open to extension without the modification of existing code takes time and effort. Following the Open-Closed Principle usually introduces new levels of abstraction, which adds complexity to our code.
You want to concentrate on those areas that are most likely to change in your designs and apply the principles there. Q: How do I know which areas of change are more important? A: That is partly a matter of experience in designing OO systems and also a matter of the knowing the domain you are working in. Looking at other examples will help you learn to identify areas of change in your own designs.
A: While it may seem like a contradiction, there are techniques for allowing code to be extended without direct modification. Many of the patterns give us time tested designs that protect your code from being modified by supplying a means of extension.
How can I make every part of my design follow the Open-Closed Principle? Remember us? Starbuzz Coffee? Do you think you could use some of those design principles to actually help us?
cost DarkRoast 2 head first design patterns pdf download DarkRoaasnd has t a h t r e b Remem from Beverage mputes inherits method that co a cost of the drink. the cost The customer wants Mocha, so we create a Mocha object and wrap it around the DarkRoast. Its ject is a decorisatdecorating, The Mocha obth object it type mirrors Beeverage.
we mean it is cost cost DarkRoast Mocha 3 oo, st method tn treat co a s a h a ch o e ca So, M olymorphism w and through p wrapped in Mocha as any Beveragetoo because Mocha is a a Beverage, Beverage. subtype of The customer also wants Whip, so we create a Whip decorator and wrap Mocha with it. So, a DarkRoast wrapped in Mocha and Whip is still a Beverage and we can do anything with it we can do with a DarkRoast, including call its cost method.
We do this by calling cost on the outermost decorator, Whip, and Whip is going to delegate computing the cost to the objects it decorates.
Once it gets a cost, it will add on the cost of the Whip. ge a few pa Mocha. cost t. ß Decorators have the same supertype as the objects they decorate. ß You can use one or more decorators to wrap an object. ß Given that the decorator has the same supertype as the object it decorates, we can pass around a decorated object in place of the original wrapped object.
ß Objects can be decorated at any time, so we can decorate objects dynamically at runtime with as many decorators as we like. Decorators provide a flexible alternative to subclassing for extending functionality. Each component can be used on its own, or wrapped by a decorator.
It extends Component. ent the Decorators implem abstract same interfacemorponent they class as the co corate. th en on mp state of the co Decorators can add new methods; however, new behavior is typically added by doing computation before or after an existing method in head first design patterns pdf download component. r Beverage acts asneou class. coffe Milk Whip Soy Mocha Beverage beverage Beverage beverage Beverage beverage Beverage beverage cost cost cost cost getDescription getDescription getDescription getDescription And here are our condiment decorators; notice they need to implement not only cost but also getDescription.
Sue: What do you mean? Mary: Look at the class diagram. The CondimentDecorator is extending the Beverage class.
Design Patterns: Strategy
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Books. Contribute to ajitpal/BookBank development by creating an account on GitHub Download Full Head First Design Patterns Book in PDF, EPUB, Mobi and All Ebook Format. You also can read online Head First Design Patterns and write the review about the book downloads Views 1MB Size Report. DOWNLOAD PDF. 3 the DecoratorPattern g Decorating h Objects g I used to think real men subclassed everything. Download at blogger.com Praise for Head First Design Patterns “I received the book yesterday and started to read it Estimated Reading Time: 8 mins
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