Design Patterns Explained

More documents

Recommendations

Info

$MATLAB C++ Math Library Reference$

Or again, people are creatures of habit. If they pass in and out of the courtyard, every day, in the course of their normal lives, the courtyard becomes familiar, a natural place to go … and it is used. But a courtyard with only one way in, a place you only go when you “want” to go there, is an unfamiliar place, tends to stay unused… people go more often to places which are familiar. Or again, there is a certain abruptness about suddenly stepping out, from the inside, directly to the outside … it is subtle, but enough to inhibit you. If there is a transitional space—a porch or a veranda, under cover, but open to the air—this is psychologically half way between indoors and outdoors, and makes it much easier, more simple, to take each of the smaller steps that brings you out into the courtyard… When a courtyard has a view out to a larger space, has crossing paths from different rooms, and has a veranda or a porch, these forces can resolve themselves. The view out makes it comfortable, the crossing paths help generate a sense of habit there, the porch makes it easier to go out more often … and gradually the courtyard becomes a pleasant customary place to be. The four components required of every pattern description Patterns exist for almost any design problem and may be combined to solve complex problems Familiarity sometimes keeps us from seeing the obvious. The value of a pattern is that those with less experience can take advantage of what others have learned before them: • both what must be included to have a good design. • and what must be avoided to keep from a poor design.. A solution to a possibly overlooked challenge to building a great courtyard Alexander is telling us how to build a great courtyard …and then tells us why it is great. To review, Alexander says that a description of a pattern involves four items: • The name of the pattern. • The purpose of the pattern, the problem it solves. • How we could accomplish this. • The constraints and forces we have to consider in order to accomplish it. Alexander postulated that patterns exist which solve virtually every architectural problem that one will encounter. He further postulated that patterns could be used together to solve complex architectural problems. How patterns work together will be discussed later in this book. For now, I want to focus on his claim that patterns are useful to solve specialized problems.
Moving from Architectural to Software Design Patterns The Hillside Group adapted Alexander for software The Gang of Four did the early work on Design Patterns What does all of this architectural stuff have to do with us software developers? Well, in the early 90s some experienced developers happened upon Alexander’s work in patterns. They wondered if what was true for architectural patterns would also be true for software design. 2 • Were there problems in software that occur over and over again that could be solved in somewhat the same manner? • Was it possible to design software in terms of patterns, creating specific solutions based on these patterns only after the patterns had been identified? The group felt the answer to both of these questions was “unequivocally yes”. The next step was to identify several patterns and develop standards for cataloging new ones. Although many people were working on design patterns in the early 90s, the book that had the greatest influence on this fledging community was Design Patterns: Elements of Reusable Object-Oriented Software by Gamma, Helm, Johnson, Vlissides [Gamma 1995]. In recognition of their important work, these four authors are commonly and affectionately known as the “Gang of Four.” This book served several purposes. • It defined what design patterns were within the area of software design. • It described a structure within which to catalog and describe design patterns. • It cataloged 23 such patterns. • It postulated object-oriented strategies and approaches based on these design patterns. It is important to realize that the patterns described in the book were not created by the authors. Rather, the authors identified these patterns as already existing within the software community, patterns that reflected what had been learned about high quality designs for specific problems (note the similarity to Alexander’s work). Today, there are several different forms for describing design patterns. In some circles, the Gang of Four’s structure is considered to be obsolete. Since 2 The ESPRIT consortium in Europe was doing similar work in the 1980’s. Project 1098 and Project 5248 developed a pattern-based design methodology called Knowledge Analysis and Design Support (KADS). See Cognitive Patterns: Problem-Solving Frameworks for Object Technology, Karen Gardner, et.al. Cambridge University Press. 1998.
Page 1 and 2:
------==Proudly Presented by MODELE
Page 3 and 4:
xvi Preface From Object Orientation
Page 5 and 6:
xviii Preface Patterns are supposed
Page 7 and 8:
xx Preface A slight digression. The
Page 9 and 10:
xxii Preface abstractly and because
Page 11 and 12:
xxiv Preface Approach Rationale A N
Page 13 and 14:
xxvi Preface Acknowledgments Almost
Page 16 and 17:
Overview CHAPTER 1 The Object-Orien
Page 18 and 19:
Chapter 1 The Object-Oriented Parad
Page 20 and 21:
Page 22 and 23:
Page 24 and 25:
Page 26 and 27:
Page 28 and 29:
Table 1-2 Objects and Their Respons
Page 30 and 31:
Page 32 and 33:
Page 34 and 35:
Page 36 and 37:
The main program would now look lik
Page 38 and 39:
Page 40 and 41:
Table 1-4 Object-Oriented Terminolo
Page 42 and 43:
3O Part I • An Introduction to Ob
Page 44 and 45:
32 Part I • An Introduction to Ob
Page 46 and 47:
Page 48 and 49:
Page 50 and 51:
Page 52 and 53:
4O Part I • An Introduction to Ob
Page 54 and 55:
PART II The Limitations of Traditio
Page 56 and 57:
CHAPTER 3 A Problem That Cries Out
Page 58 and 59:
Chapter 3 • A Problem That Cries
Page 60 and 61:
Page 62 and 63:
Page 64 and 65:
Figure 3-6 Class diagram of my solu
Page 66 and 67:
Summary Chapter 3 • A Problem Tha
Page 68 and 69:
58 Part II • The Limitations of T
Page 70 and 71:
6O Part II • The Limitations of T
Page 72 and 73:
Chapter 4 • A Standard Object-Ori
Page 74 and 75:
Chapter 4 • A Standard Object-Ori
Page 76 and 77:
Example 4-6 C++ Code Fragments: Imp
Page 78 and 79:
Part Overview PART III Design Patte
Page 80 and 81:
Overview CHAPTER 5 An Introduction
Page 82 and 83:
Chapter 5 An Introduction to Design
Page 84 and 85:
Page 86 and 87:
Page 88 and 89:
Table 5-2 Key Features of Patterns
Page 90 and 91:
Page 92 and 93:
Figure 5-2 A miter joint Chapter 5
Page 94 and 95:
Page 96 and 97:
Overview CHAPTER 6 The Facade Patte
Page 98 and 99:
This person would determine how I a
Page 100 and 101:
Field Notes: The Facade Pattern Fac
Page 102 and 103:
Summary Chapter 6 • The Facade Pa
Page 104 and 105:
96 Part III • Design Patterns Int
Page 106 and 107:
98 Part III • Design Patterns How
Page 108 and 109:
1OO Part III • Design Patterns /
Page 110 and 111:
1O2 Part III • Design Patterns Th
Page 112 and 113:
1O4 Part III • Design Patterns Co
Page 114 and 115:
1O6 Part III • Design Patterns Ad
Page 116 and 117:
CHAPTER 8 Expanding Our Horizons Ov
Page 118 and 119:
1. Make a preliminary design withou
Page 120 and 121:
Chapter 8 • Expanding Our Horizon
Page 122 and 123:
Page 124 and 125:
Page 126 and 127:
Page 128 and 129:
Page 130 and 131:
124 Part III • Design Patterns It
Page 132 and 133:
126 Part III Design Patterns Proper
Page 134 and 135:
128 Part III Design Patterns But, t
Page 136 and 137:
130 Part III Design Patterns Unders
Page 138 and 139:
132 Part III Design Patterns This s
Page 140 and 141:
134 Part III Design Patterns An alt
Page 142 and 143:
136 Part III Design Patterns It sti
Page 144 and 145:
138 Part III Design Patterns Learni
Page 146 and 147:
140 Part III Design Patterns Strate
Page 148 and 149:
142 Part III Design Patterns Tying
Page 150 and 151:
144 Part III Design Patterns One ru
Page 152 and 153:
146 Part III Design Patterns From a
Page 154 and 155:
148 Part III Design Patterns Exampl
Page 156 and 157:
150 Part III Design Patterns The es
Page 158 and 159:
152 Part III Design Patterns Compou
Page 160 and 161:
154 Part III Design Patterns A usef
Page 162 and 163:
156 Part III Design Patterns Concep
Page 164 and 165:
Page 166 and 167:
Page 168 and 169:
CHAPTER 10 The Abstract Factory Pat
Page 170 and 171:
Chapter 1O • The Abstract Factory
Page 172 and 173:
Page 174 and 175:
Page 176 and 177:
Figure 1O-5 The ResFactory encapsul
Page 178 and 179:
Figure 1O-6 Intermediate solution u
Page 180 and 181:
In this pattern, Chapter 1O • The
Page 182 and 183:
Page 184 and 185:
Page 186 and 187:
Page 188 and 189:
CHAPTER 11 How Do Experts Design? O
Page 190 and 191:
Design is often thought of as a pro
Page 192 and 193:
Design is often thought of as a pro
Page 194 and 195:
It is only possible to make a place
Page 196 and 197:
that it shared its patterns with ot
Page 198 and 199:
Alexander's Steps Discussion Identi
Page 200 and 201:
Chapter 11 • How Do Experts Desig
Page 202 and 203:
198 Part IV • Putting It All Toge
Page 204 and 205:
2OO Part IV • Putting It All Toge
Page 206 and 207:
2O2 Part IV • Putting It All Toge
Page 208 and 209:
2O4 Part IV • Putting It AM Toget
Page 210 and 211:
Chapter 12 • Solving the CAD/CAM
Page 212 and 213:
Page 214 and 215:
Page 216 and 217:
Page 218 and 219:
Page 220 and 221:
CHAPTER 13 The Principles and Strat
Page 222 and 223:
Chapter 13 • The Principles and S
Page 224 and 225:
Page 226 and 227:
Page 228 and 229:
Page 230 and 231:
228 Part V • Handling Variations
Page 232 and 233:
23O Part V • Handling Variations
Page 234 and 235:
Page 236 and 237:
Page 238 and 239:
Page 240 and 241:
Page 242 and 243:
Page 244 and 245:
Page 246 and 247:
Page 248 and 249:
Page 250 and 251:
Page 252 and 253:
Page 254 and 255:
Page 256 and 257:
Page 258 and 259:
Page 260 and 261:
Page 262 and 263:
Page 264 and 265:
Page 266 and 267:
Page 268 and 269:
Page 270 and 271:
Page 272 and 273:
Page 274 and 275:
Page 276 and 277: 274 Part V • Handling Variations
Page 280 and 281: Overview CHAPTER 18 The Template Me
Page 282 and 283: Chapter 18 • The Template Method
Page 284 and 285: Intent Problem Solution Participant
Page 286 and 287: CHAPTER 19 The Factory Method Patte
Page 288 and 289: The Factory Method Pattern Chapter
Page 290 and 291: Summary Chapter 19 • The Factory
Page 300 and 301: Figure 2O-1 Using Strategy patterns
Page 302 and 303: 3O2 Part V • Handling Variations
Page 304 and 305: CHAPTER 21 Design Patterns Reviewed
Page 306 and 307: Chapter 21 • Design Patterns Revi
Page 308 and 309: Chapter 21 • Design Patterns Revi
Page 310 and 311: Figure 21-1 The relationships betwe
Page 312 and 313: CHAPTER 22 Bibliography This book h
Page 314 and 315: • Meyer, B., Object-Oriented Soft
Page 316 and 317: • See http://java.sun.com/j2se/L3
Page 318 and 319: Personal Favorites It is my belief
Page 320 and 321: Spradely, J. P., The Ethnographic I
Page 322 and 323: Section Overview Section 3: Design
Page 324 and 325: How do we get good quality repeated
Page 328 and 329: this book is not a book about writi
Page 330 and 331: …The details can confuse the solu
Page 332 and 333: Patterns help us see the forest for
Page 334 and 335: Design Pattern Matrix Design Patter
Page 336 and 337: Design Pattern Matrix How it is imp
Page 344 and 345: Design Pattern Matrix Is there vari
Page 346 and 347: : (colon), connecting object and cl
Page 348 and 349: usiness rules defining, 238 encapsu
Page 350 and 351: decompression object, 249 decorator
Page 352 and 353: FilterlnputStream class, 250 flexib
Page 354 and 355: notifyObservers method, 272 NULL te
Page 356 and 357: sales-order architecture, e-tail sy
show all

Design Patterns Explained

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?