Pro PHP Refactoring (eBook)

Francesco Trucchia worked some years as web engineer on small, medium and large projects for international companies. Now he is the co-founder and chief technology officer of Ideato Srl, an Italian company in the business of web software development and agile methods. He likes to develop with extreme programming (XP) methods (test-driven design, pair programming, KISS, etc.) and he has introduced these practices in Ideato with a lot of positive feedback about the software life cycle process. Francesco specializes in web engineering, web development, ITC consultant, ITC problem solving, symfony development, PHP development, project management, XP methods, and agile processes.

Title Page 
1 
Copyright Page 
2 
Contents at a Glance 3
Table of Contents 
4 
About the Authors 18
About the Technical Reviewer 19
Acknowledgments 20
Introduction 21
CHAPTER 1 Introduction 
22 
Lesson Learned 23
Hidden Gems 23
You Don’t Know What You’ve Got ’til It’s Gone 23
Call of Duty 24
CHAPTER 2 Finding “Bad Smells” in Code 
25 
Why Code Can Smell 25
Duplicated Code 26
Long Method 27
Large Class 30
Long Parameter List 32
Divergent Change 33
Shotgun Surgery 35
Feature Envy 35
Data Clamps 36
Primitive Obsession 37
Switch Statements 38
Lazy Class 39
Speculative Generality 40
Temporary Field 40
Data Class 41
Comments 42
Procedural Code 44
CHAPTER 3 Introduction to Refactoring 
45 
The Concept: What Refactoring Is 45
The Reason: What’s the Goal of Refactoring? 45
Architecture and Structure, They Fade Away 46
Reworking Chaos into Well-Designed Code 46
An Example, at Last 47
Look Ma’! No Comments! 51
Once Is Better than Twice 53
Goliath Died in the End 55
CHAPTER 4 Principles and Rules 
67 
Why Should You Do Refactoring? 67
Refactoring Improves the Design of Our Software 67
Refactoring Makes Software Easier to Understand 68
Keep It Simple and Stupid (KISS) 68
Don’t Repeat Yourself 69
Test-Driven Development (TDD) 69
Refactoring Helps You Find Bugs 69
Refactoring Increases Our Productivity 70
When Should We Do Refactoring? 71
The Rule of Three 71
Refactoring When You Add Functionality 72
Refactoring When You Need to Fix a Bug 72
When You Shouldn’t Do Refactoring 73
Some Simple Rules 73
Test Before Refactoring 73
Small and Simple Changes 74
Never Change Functionality 74
Follow the Bad Smells 74
Follow Refactoring Techniques Step-by-Step 75
Summary 75
CHAPTER 5 Test-First Development 
76 
Building Value One-Way 76
Chaos in a Cage 77
Unit Tests 77
Functional Tests 77
You Don't Know What You’ve Got ’til It’s Gone 78
Trust Me: Communication 78
Listen to What You Say, and Write It Down 79
Pleasant Constraints 79
Create Trust 80
Test-Driven Development 80
Summary 81
CHAPTER 6 Refactoring Tools 
82 
PHP IDE 82
Refactoring Activities 82
Rename 82
Move 83
Encapsulate Field 83
Override 83
Safely Remove 83
Cross-Platform Open-Source IDE 83
Unit Tests with PHPUnit 83
What Is It? 83
Installation 84
PEAR Installation 84
Manual Installation 84
How to Write Unit Tests 85
How to Run Tests 89
How to Organize Our Tests 90
Test Doubles 93
Stub Object 94
Mock Object 95
PHPUnit Conclusion 96
Functional Test with Selenium 96
What Is It? 96
Selenium IDE 97
Selenium RC 97
Selenium Grid 97
Installation 97
How to Record and Run Functional Tests 98
How to Organize Selenium Tests 100
Automated Test Execution with Selenium RC 101
Selenium Conclusion 101
The Best of Two Worlds 101
Selenium RC and PHPUnit 101
Selenium Functional Test with PHPUnit 101
Summary 103
CHAPTER 7 Structuring Behavior 
104 
Extract Method 104
Motivation 104
Mechanics 105
Example: No Local Variables 105
Example: Using Local Variables 107
Example: Reassigning a Local Variable 107
Inline Method 111
Motivation 111
Mechanics 111
Example 112
Inline Temp 113
Motivation 113
Mechanics 113
Example 113
Replace Temp with Query 114
Motivation 114
Mechanics 114
Example 115
Introduce Explaining Variable 117
Motivation 117
Mechanics 117
Example 117
Split Temporary Variable 118
Motivation 118
Mechanics 119
Example 119
Replace Method with Method Object 121
Motivation 121
Mechanics 121
Example 121
Substitute Algorithm 123
Motivation 123
Mechanics 124
Example 124
Summary 125
CHAPTER 8 Changing Class Responsibilities 
126 
Move Method 126
Motivation 126
Mechanics 127
Example 127
Move Property (or Field) 131
Motivation 131
Mechanics 131
Example 132
Extract Class 134
Motivation 134
Mechanics 134
Example 135
Inline Class 140
Motivation 140
Mechanics 140
Example 140
Hide Delegate 143
Motivation 143
Mechanics 143
Example 143
Remove the Middle Man 146
Motivation 146
Mechanism 146
Example 147
Introduce Foreign Method 149
Motivation 149
Mechanism 150
Example 150
Summary 151
CHAPTER 9 Dealing with Data Rationalization 
152 
Self-Encapsulate Field 152
Motivation 152
Mechanics 152
Example 153
Replace Data Value with Object 154
Motivation 154
Mechanics 154
Example 154
Change Value to Reference 156
Motivation 156
Mechanics 156
Example 157
Change Reference to Value 159
Motivation 159
Mechanics 159
Replace Array with Object 159
Motivation 160
Mechanics 160
Example 160
Change Unidirectional Association to Bidirectional 162
Motivation 162
Mechanics 162
Example 163
Change Bidirectional Association to Unidirectional 165
Motivation 165
Mechanics 165
Example 166
Replace Magic Number with Symbolic Constant 168
Motivation 168
Mechanics 168
Example 168
Encapsulate Field 169
Motivation 169
Mechanics 170
Example 170
Replacing Type Code with Subclasses 171
Motivation 171
Mechanics 171
Example 171
Replace Type Code with State/Strategy 175
Motivation 175
Mechanics 175
Example 175
Replace Subclass with Fields 180
Motivation 180
Mechanics 180
Example 181
Summary 185
CHAPTER 10 Reducing to Essential Conditional Executions 
186 
Decompose Conditional 186
Motivation 186
Mechanics 187
Example 187
Consolidate Conditional Expression 189
Motivation 189
Mechanism 190
Example to Consolidate with ORs 190
Example to Consolidate with AND 191
Consolidate Duplicate Conditional Fragments 192
Motivation 192
Mechanism 192
Example 193
Remove Control Flag 194
Motivation 194
Mechanism 194
Example with Control Flag Replaced with Break 195
Example Replacing Control Flag with a Return Exit Point 196
Replace Nested Conditional with Guard Clauses 198
Motivation 198
Mechanism 198
Example 199
Replace Conditional with Polymorphism 201
Motivation 201
Mechanism 202
Example 202
Summary 205
CHAPTER 11 Simplifying Method Calls 
206 
Rename Method 206
Motivation 206
Mechanics 206
Example 207
Add Parameter 208
Motivation 208
Mechanics 208
Example 209
Remove Parameter 210
Motivation 210
Mechanics 210
Separate Query from Modifier 211
Motivation 211
Mechanics 211
Example 211
Parameterize Method 213
Motivation 213
Mechanics 214
Example 214
Replace Parameter with Explicit Method 215
Motivation 215
Mechanics 216
Example 216
Preserve Whole Object 218
Motivation 218
Mechanics 218
Example 219
Replace Parameter with Method 220
Motivation 221
Mechanics 221
Example 221
Introduce Parameter Object 222
Motivation 222
Mechanics 223
Remove Setting Method 223
Motivation 223
Mechanics 223
Example 223
Hide Method 225
Motivation 225
Mechanics 225
Replace Constructor with Factory Method 225
Motivation 225
Mechanics 226
Example 226
Replace Error Code with Exception 227
Motivation 227
Mechanics 227
Example 227
Replace Exception with Test 229
Motivation 229
Mechanics 229
Summary 229
CHAPTER 12 Simplifying Generalization Relationships 
230 
Pull Up Field 230
Motivation 230
Mechanism 231
Example 231
Pull Up Method 232
Motivation 232
Mechanism 233
Example 233
Pull Up Constructor Body 235
Motivation 235
Mechanism 236
Example 236
Push Down Method 239
Motivation 239
Mechanism 239
Example 239
Push Down Field 242
Motivation 242
Mechanism 242
Example 242
Extract Subclass 245
Motivation 245
Mechanism 245
Example 246
Extract Super Class 250
Motivation 250
Mechanism 250
Example 251
Collapse Hierarchy 254
Motivation 254
Mechanism 254
Example 255
Form Template Method 257
Motivation 257
Mechanism 257
Example 258
Replace Inheritance with Delegation 262
Motivation 262
Mechanism 263
Example 263
Replace Delegation with Inheritance 266
Motivation 266
Mechanism 266
Example 267
Summary 268
CHAPTER 13 Legacy Code 
269 
Ugly Code 269
index.php 272
config.php 273
functions.php 273
header.php 274
footer.php 275
new.php 275
edit.php 276
_form.php 278
remove.php 278
Maintenance 279
Example: SQL injection 279
Example: Database Portability 280
New Features 280
Dynamic Layouts 280
Internationalization 281
Break the Cycle 281
Summary 282
CHAPTER 14 Regression Tests 
283 
Ugly But Valuable 283
Keeping Value vs. Wasting Value 284
Putting the Chaos in a Cage 284
Motivation 284
Mechanics 285
Examples 285
Add a New Record 286
Edit a Record 288
Read a List of Records 289
Remove a Record 290
Validate a Record 291
Test Refactoring 292
Unify Test Cases in a Suite 293
Summary 294
CHAPTER 15 Refactoring with Patterns 
295 
Design Patterns 295
What Are Design Patterns? 295
Why Do I Need to Use Design Patterns? 296
When Do I Need to Use Them? 296
Refactoring with Patterns 296
Transform Procedural Code into Object-Oriented Code 297
Motivation 297
Mechanism 298
Example 299
Working with Fixtures 299
Index Action 300
Add Action 304
Edit Action 309
Remove Action 314
Replace SQL with ORM 316
Motivation 316
Mechanism 317
Example 317
Separate Business Logic from View 326
Motivation 326
Mechanism 326
Example 327
Decorator Design Pattern 327
Template View Pattern 333
MVC Architecture 337
Motivation 337
Mechanism 337
Example 338
Summary 345
Index 346