Файл: Programming_in_Scala,_2nd_edition.pdf

List of Tables

xxv

24.11

Performance characteristics of set and map types . . . . . .

586

24.12

Operations in trait Iterator . . . . . . . . . . . . . . . .

595

24.13

Factory methods for sequences . . . . . . . . . . . . . . .

602

33.1

Summary of parser combinators . . . . . . . . . . . . . . .

770

3.1

Parameterizing an array with a type. . . . . . . . . . . . .

82

3.2

Creating and initializing an array. . . . . . . . . . . . . . .

85

3.3

Creating and initializing a list. . . . . . . . . . . . . . . . .

86

3.4

Creating and using a tuple. . . . . . . . . . . . . . . . . .

90

3.5

Creating, initializing, and using an immutable set. . . . . .

91

3.6

Creating, initializing, and using a mutable set. . . . . . . .

93

3.7

Creating, initializing, and using a mutable map. . . . . . .

94

3.8

Creating, initializing, and using an immutable map. . . . .

95

3.9

A function without side effects or vars. . . . . . . . . . . .

97

3.10

Reading lines from a file. . . . . . . . . . . . . . . . . . .

99

3.11

Printing formatted character counts for the lines of a file. .

102

4.1

Final version of class ChecksumAccumulator. . . . . . . .

107

4.2

Companion object for class ChecksumAccumulator. . . . .

110

4.3

The Summer application. . . . . . . . . . . . . . . . . . . .

112

4.4

Using the Application trait. . . . . . . . . . . . . . . . .

115

6.1

Rational with fields. . . . . . . . . . . . . . . . . . . . .

145

6.2

Rational with an auxiliary constructor. . . . . . . . . . .

147

6.3

Rational with a private field and method. . . . . . . . . .

148

6.4

Rational with operator methods. . . . . . . . . . . . . . .

150

6.5

Rational with overloaded methods. . . . . . . . . . . . .

155

7.1

Scala’s idiom for conditional initialization. . . . . . . . . .

160

7.2

Calculating greatest common divisor with a while loop. . .

161

7.3

Reading from the standard input with do-while. . . . . . .

162

7.4

Calculating greatest common divisor with recursion. . . . .

163

7.5

Listing files in a directory with a for expression. . . . . . .

164

List of Listings

xxvii

7.6

Finding .scala files using a for with a filter. . . . . . . .

166

7.7

Using multiple filters in a for expression. . . . . . . . . .

166

7.8

Using multiple generators in a for expression. . . . . . . .

167

7.9

Mid-stream assignment in a for expression. . . . . . . . .

168

7.10

Transforming an Array[File] to Array[Int] with a for.

169

7.11

A try-catch clause in Scala. . . . . . . . . . . . . . . . .

171

7.12

A try-finally clause in Scala. . . . . . . . . . . . . . .

172

7.13

A catch clause that yields a value. . . . . . . . . . . . . .

173

7.14

A match expression with side effects. . . . . . . . . . . . .

174

7.15

A match expression that yields a value. . . . . . . . . . . .

174

7.16

Looping without break or continue. . . . . . . . . . . . .

176

7.17

A recursive alternative to looping with vars. . . . . . . . .

176

7.18

Variable scoping when printing a multiplication table. . . .

179

7.19

A functional way to create a multiplication table. . . . . . .

182

8.1

LongLines with a private processLine method. . . . . . .

185

8.2

LongLines with a local processLine function. . . . . . .

187

8.3

A parameter with a default value. . . . . . . . . . . . . . .

201

8.4

A function with two parameters that have defaults. . . . . .

202

9.1

Using closures to reduce code duplication. . . . . . . . . .

211

9.2

Defining and invoking a “plain old” function. . . . . . . . .

214

9.3

Defining and invoking a curried function. . . . . . . . . . .

214

9.4

Using the loan pattern to write to a file. . . . . . . . . . . .

218

9.5

Using a by-name parameter. . . . . . . . . . . . . . . . . .

219

10.1

Defining an abstract method and class. . . . . . . . . . . .

224

10.2

Defining parameterless methods width and height. . . . .

225

10.3

Defining ArrayElement as a subclass of Element. . . . . .

227

10.4

Overriding a parameterless method with a field. . . . . . .

229

10.5

Defining contents as a parametric field. . . . . . . . . . .

231

10.6

Invoking a superclass constructor. . . . . . . . . . . . . . .

232

10.7

Declaring a final method. . . . . . . . . . . . . . . . . . .

238

10.8

Declaring a final class. . . . . . . . . . . . . . . . . . . . .

238

10.9

Class Element with above, beside, and toString. . . . .

243

10.10

A factory object with factory methods. . . . . . . . . . . .

244

10.11

Class Element refactored to use factory methods. . . . . .

245

10.12

Hiding implementation with private classes. . . . . . . . .

246

List of Listings

xxviii

10.13

Element with widen and heighten methods. . . . . . . .

247

10.14

The Spiral application. . . . . . . . . . . . . . . . . . . .

248

12.1

The definition of trait Philosophical. . . . . . . . . . . .

258

12.2

Mixing in a trait using extends. . . . . . . . . . . . . . .

259

12.3

Mixing in a trait using with. . . . . . . . . . . . . . . . .

260

12.4

Mixing in multiple traits. . . . . . . . . . . . . . . . . . .

260

12.5

Defining an enrichment trait. . . . . . . . . . . . . . . . .

264

12.6

Abstract class IntQueue. . . . . . . . . . . . . . . . . . .

268

12.7

A BasicIntQueue implemented with an ArrayBuffer. . .

268

12.8

The Doubling stackable modification trait. . . . . . . . . .

269

12.9

Mixing in a trait when instantiating with new. . . . . . . . .

270

12.10

Stackable modification traits Incrementing and Filtering.

270

13.1

Placing the contents of an entire file into a package. . . . .

278

13.2

Long form of a simple package declaration. . . . . . . . .

278

13.3

Multiple packages in the same file. . . . . . . . . . . . . .

279

13.4

Concise access to classes and packages. . . . . . . . . . . .

279

13.5

Symbols in enclosing packages not automatically available.

280

13.6

Accessing hidden package names. . . . . . . . . . . . . . .

280

13.7

Bob’s delightful fruits, ready for import. . . . . . . . . . .

283

13.8

Importing the members of a regular (not singleton) object. .

283

13.9

Importing a package name. . . . . . . . . . . . . . . . . .

284

13.10

How private access differs in Scala and Java. . . . . . . . .

287

13.11

How protected access differs in Scala and Java. . . . . . . .

288

13.12

Flexible scope of protection with access qualifiers. . . . . .

289

13.13

Accessing private members of companion classes and objects.

292

13.14

A package object. . . . . . . . . . . . . . . . . . . . . . .

293

14.1

Using an assertion. . . . . . . . . . . . . . . . . . . . . . .

296

14.2

Using ensuring to assert a function’s result. . . . . . . . .

296

14.3

Writing a test method with Suite. . . . . . . . . . . . . .

297

14.4

Writing a test function with FunSuite. . . . . . . . . . . .

298

14.5

Writing a JUnit test with JUnit3Suite. . . . . . . . . . .

301

14.6

Writing a TestNG test with TestNGSuite. . . . . . . . . .

302

14.7

Specifying and testing behavior with a ScalaTest FlatSpec.

303

14.8

Specifying and testing behavior with the specs framework. .

304

14.9

Writing property-based tests with ScalaCheck. . . . . . . .

305

List of Listings

xxix

15.1

Defining case classes. . . . . . . . . . . . . . . . . . . . .

310

15.2

The simplifyTop function, which does a pattern match. . .

312

15.3

A pattern match with an empty “default” case. . . . . . . .

314

15.4

A pattern match with wildcard patterns. . . . . . . . . . . .

315

15.5

A pattern match with constant patterns. . . . . . . . . . . .

315

15.6

A pattern match with a variable pattern. . . . . . . . . . . .

316

15.7

A pattern match with a constructor pattern. . . . . . . . . .

318

15.8

A sequence pattern with a fixed length. . . . . . . . . . . .

318

15.9

A sequence pattern with an arbitrary length. . . . . . . . .

319

15.10

A pattern match with a tuple pattern. . . . . . . . . . . . .

319

15.11

A pattern match with typed patterns. . . . . . . . . . . . .

320

15.12

Using isInstanceOf and asInstanceOf (poor style). . . .

321

15.13

A pattern with a variable binding (via the @ sign). . . . . .

323

15.14

A match expression with a pattern guard. . . . . . . . . . .

324

15.15

Match expression in which case order matters. . . . . . . .

325

15.16

A sealed hierarchy of case classes. . . . . . . . . . . . . .

327

15.17

Defining multiple variables with one assignment. . . . . . .

330

15.18

A for expression with a tuple pattern. . . . . . . . . . . .

334

15.19

Picking elements of a list that match a pattern. . . . . . . .

334

15.20

The top half of the expression formatter. . . . . . . . . . .

337

15.21

The bottom half of the expression formatter. . . . . . . . .

338

15.22

An application that prints formatted expressions. . . . . . .

341

16.1

A merge sort function for Lists. . . . . . . . . . . . . . .

360

17.1

Default map and set definitions in Predef. . . . . . . . . .

382

18.1

A mutable bank account class. . . . . . . . . . . . . . . . .

400

18.2

A class with public vars. . . . . . . . . . . . . . . . . . .

402

18.3

How public vars are expanded into getter and setter methods.

403

18.4

Defining getter and setter methods directly. . . . . . . . . .

403

18.5

Defining a getter and setter without an associated field. . .

404

18.6

The halfAdder method. . . . . . . . . . . . . . . . . . . .

407

18.7

The fullAdder method. . . . . . . . . . . . . . . . . . . .

408

18.8

The Simulation class. . . . . . . . . . . . . . . . . . . .

410

18.9

The first half of the BasicCircuitSimulation class. . . .

414

18.10

The second half of the BasicCircuitSimulation class. .

415

18.11

The CircuitSimulation class. . . . . . . . . . . . . . . .

419