Programming in Go. Creating Applications for the 21st Century

480 Pages·2012·4.662 MB·english

by  Mark Summerfield

Programming in Go
Creating Applicationsfor the 21st Century
Mark Summerfield
VisitusontheWeb:informit.com/aw
Libraryof CongressCataloging-in-PublicationData
Summerfield,Mark.
ProgramminginGo:creatingapplicationsforthe21stcentury/MarkSummerfield.
p.mcm.
Includesbibliographicalreferencesandindex.
ISBN978-0-321-77463-7 (pbk.:alk. paper)
1. Go(Computerprogramlanguage) 2. Computerprogramming 3. Applicationsoftware—
Development I.Title.
QA76.73.G63S86 2012
005.13’3—dc23
2012001914
Copyright©2012QtracLtd.
ISBN-13: 978-0-321-77463-7
ISBN-10: 0-321-77463-9
TextprintedintheUnitedStatesonrecycledpaperatRRDonnelleyinCrawfordsville,Indiana.
Firstprinting,April2012
Contents at a Glance
Tables .............................................................. xv
Introduction ...................................................... 1
Chapter1. AnOverviewinFiveExamples ...................... 7
Chapter2. BooleansandNumbers................................ 51
Chapter3. Strings ................................................ 81
Chapter4. CollectionTypes ...................................... 139
Chapter5. ProceduralProgramming ............................ 185
Chapter6. Object-OrientedProgramming ...................... 253
Chapter7. ConcurrentProgramming ............................ 315
Chapter8. FileHandling .......................................... 361
Chapter9. Packages .............................................. 407
AppendixA. Epilogue ............................................ 435
AppendixB. TheDangersof SoftwarePatents .................. 437
AppendixC. SelectedBibliography .............................. 441
Index .............................................................. 443
www.qtrac.eu/gobook.html
Contents
Tables .............................................................. xv
Introduction ...................................................... 1
WhyGo? ........................................................ 1
TheStructureof theBook ........................................ 4
Acknowledgments ................................................ 5
Chapter1. AnOverviewinFiveExamples ........................ 7
1.1. GettingGoing ................................................ 7
1.2. Editing,Compiling,andRunning ............................ 9
1.3. HelloWho? .................................................. 14
1.4. BigDigits—Two-DimensionalSlices .......................... 16
1.5. Stack—CustomTypeswithMethods .......................... 21
1.6. Americanise—Files,Maps,andClosures ...................... 29
1.7. PolartoCartesian—Concurrency ............................ 40
1.8. Exercise .................................................... 48
Chapter2. BooleansandNumbers ................................ 51
2.1. Preliminaries ................................................ 51
2.1.1. ConstantsandVariables ................................ 53
2.1.1.1. Enumerations ...................................... 54
2.2. BooleanValuesandExpressions .............................. 56
2.3. NumericTypes .............................................. 57
2.3.1. IntegerTypes .......................................... 59
2.3.1.1. BigIntegers........................................ 61
2.3.2. Floating-PointTypes .................................... 64
2.3.2.1. ComplexTypes .................................... 70
2.4. Example:Statistics .......................................... 72
2.4.1. ImplementingSimpleStatisticsFunctions................ 73
2.4.2. ImplementingaBasicHTTPServer ...................... 75
2.5. Exercises .................................................... 78
Chapter3. Strings ................................................ 81
3.1. Literals,Operators,andEscapes .............................. 83
3.2. ComparingStrings .......................................... 86
3.3. CharactersandStrings ...................................... 87
3.4. IndexingandSlicingStrings .................................. 90
3.5. StringFormattingwiththeFmtPackage ...................... 93
3.5.1. FormattingBooleans .................................... 97
3.5.2. FormattingIntegers .................................... 98
3.5.3. FormattingCharacters .................................. 99
3.5.4. FormattingFloating-PointNumbers .................... 100
3.5.5. FormattingStringsandSlices............................ 101
3.5.6. FormattingforDebugging .............................. 103
3.6. OtherString-RelatedPackages .............................. 106
3.6.1. TheStringsPackage .................................... 107
3.6.2. TheStrconvPackage .................................... 113
3.6.3. TheUtf8Package ...................................... 117
3.6.4. TheUnicodePackage .................................... 118
3.6.5. TheRegexpPackage .................................... 120
3.7. Example:M3u2pls .......................................... 130
3.8. Exercises .................................................... 135
Chapter4. CollectionTypes ...................................... 139
4.1. Values,Pointers,andReferenceTypes ........................ 140
4.2. ArraysandSlices ............................................ 148
4.2.1. IndexingandSlicingSlices .............................. 153
4.2.2. IteratingSlices.......................................... 154
4.2.3. ModifyingSlices ........................................ 156
4.2.4. SortingandSearchingSlices ............................ 160
4.3. Maps ........................................................ 164
4.3.1. CreatingandPopulatingMaps .......................... 166
4.3.2. MapLookups .......................................... 168
4.3.3. ModifyingMaps ........................................ 169
4.3.4. Key-OrderedMapIteration .............................. 170
4.3.5. MapInversion .......................................... 170
4.4. Examples .................................................... 171
4.4.1. Example:GuessSeparator .............................. 171
4.4.2. Example:WordFrequencies.............................. 174
4.5. Exercises .................................................... 180
Chapter5. ProceduralProgramming ............................ 185
5.1. StatementBasics ............................................ 186
5.1.1. TypeConversions ...................................... 190
5.1.2. TypeAssertions ........................................ 191
5.2. Branching .................................................. 192
5.2.1. If Statements .......................................... 192
5.2.2. SwitchStatements ...................................... 195
5.2.2.1. ExpressionSwitches................................ 195
5.2.2.2. TypeSwitches...................................... 197
5.3. LoopingwithForStatements ................................ 203
5.4. CommunicationandConcurrencyStatements ................ 205
5.4.1. SelectStatements ...................................... 209
5.5. Defer,Panic,andRecover .................................... 212
5.5.1. PanicandRecover ...................................... 213
5.6. CustomFunctions ............................................ 219
5.6.1. FunctionArguments .................................... 220
5.6.1.1. FunctionCallsasFunctionArguments .............. 220
5.6.1.2. VariadicFunctions ................................ 221
5.6.1.3. FunctionswithMultipleOptionalArguments ........ 222
5.6.2. Theinit()andmain()Functions .......................... 224
5.6.3. Closures ................................................ 225
5.6.4. RecursiveFunctions .................................... 227
5.6.5. ChoosingFunctionsatRuntime .......................... 230
5.6.5.1. BranchingUsingMapsandFunctionReferences .... 230
5.6.5.2. DynamicFunctionCreation ........................ 231
5.6.6. GenericFunctions ...................................... 232
5.6.7. HigherOrderFunctions ................................ 238
5.6.7.1. MemoizingPureFunctions ........................ 241
5.7. Example: IndentSort ........................................ 244
5.8. Exercises .................................................... 250
Chapter6. Object-OrientedProgramming ...................... 253
6.1. KeyConcepts ................................................ 254
6.2. CustomTypes................................................ 256
6.2.1. AddingMethods ........................................ 258
6.2.1.1. OverridingMethods ................................ 261
6.2.1.2. MethodExpressions ................................ 263
6.2.2. ValidatedTypes ........................................ 263
6.3. Interfaces.................................................... 265
6.3.1. InterfaceEmbedding .................................... 270
6.4. Structs ...................................................... 275
6.4.1. StructAggregationandEmbedding ...................... 275
6.4.1.1. EmbeddingValues ................................ 276
6.4.1.2. EmbeddingAnonymousValuesThatHaveMethods .. 277
6.4.1.3. EmbeddingInterfaces .............................. 279
6.5. Examples .................................................... 282
6.5.1. Example:FuzzyBool—ASingle-ValuedCustomType ...... 282
6.5.2. Example:Shapes—AFamilyof CustomTypes ............ 289
6.5.2.1. Package-LevelConvenienceFunctions .............. 289
6.5.2.2. AHierarchyof EmbeddedInterfaces ................ 294
6.5.2.3. FreelyComposableIndependentInterfaces .......... 294
6.5.2.4. ConcreteTypesandMethods ........................ 295
6.5.3. Example:OrderedMap—AGenericCollectionType ...... 302
6.6. Exercises .................................................... 311
Chapter7. ConcurrentProgramming ............................ 315
7.1. KeyConcepts ................................................ 317
7.2. Examples .................................................... 322
7.2.1. Example:Filter ........................................ 322
7.2.2. Example:ConcurrentGrep .............................. 326
7.2.3. Example:Thread-SafeMap .............................. 334
7.2.4. Example:ApacheReport ................................ 341
7.2.4.1. SynchronizingwithaSharedThread-SafeMap ...... 341
7.2.4.2. SynchronizingwithaMutex-ProtectedMap ........ 345
7.2.4.3. SynchronizingbyMergingLocalMapsviaChannels 347
7.2.5. Example:FindDuplicates .............................. 349
7.3. Exercises .................................................... 357
Chapter8. FileHandling .......................................... 361
8.1. CustomDataFiles .......................................... 362
8.1.1. HandlingJSONFiles .................................... 365
8.1.1.1. WritingJSONFiles ................................ 366
8.1.1.2. ReadingJSONFiles ................................ 368
8.1.2. HandlingXMLFiles .................................... 371
8.1.2.1. WritingXMLFiles ................................ 371
8.1.2.2. ReadingXMLFiles ................................ 375
8.1.3. HandlingPlainTextFiles................................ 377
8.1.3.1. WritingPlainTextFiles ............................ 378
8.1.3.2. ReadingPlainTextFiles ............................ 380
8.1.4. HandlingGoBinaryFiles................................ 385
8.1.4.1. WritingGoBinaryFiles ............................ 385
8.1.4.2. ReadingGoBinaryFiles ............................ 386
8.1.5. HandlingCustomBinaryFiles .......................... 387
8.1.5.1. WritingCustomBinaryFiles ...................... 388
8.1.5.2. ReadingCustomBinaryFiles ...................... 392
8.2. ArchiveFiles ................................................ 397
8.2.1. CreatingZipArchives .................................. 397
8.2.2. CreatingOptionallyCompressedTarballs ................ 399
8.2.3. UnpackingZipArchives ................................ 401
8.2.4. UnpackingOptionallyCompressedTarballs .............. 403
8.3. Exercises .................................................... 405
Chapter9. Packages .............................................. 407
9.1. CustomPackages ............................................ 408
9.1.1. CreatingCustomPackages .............................. 408
9.1.1.1. Platform-SpecificCode.............................. 410
9.1.1.2. DocumentingPackages ............................ 411
9.1.1.3. UnitTestingandBenchmarkingPackages .......... 414
9.1.2. ImportingPackages .................................... 416
9.2. Third-PartyPackages ........................................ 417
9.3. ABrief Surveyof Go’sCommands ............................ 418
9.4. ABrief Surveyof theGoStandardLibrary .................... 419
9.4.1. ArchiveandCompressionPackages ...................... 419
9.4.2. BytesandString-RelatedPackages ...................... 419
9.4.3. CollectionPackages .................................... 421
9.4.4. File,OperatingSystem,andRelatedPackages ............ 423
9.4.4.1. FileFormat-RelatedPackages ...................... 424
9.4.5. Graphics-RelatedPackages .............................. 425
9.4.6. MathematicsPackages .................................. 425
9.4.7. MiscellaneousPackages ................................ 425
9.4.8. NetworkingPackages .................................. 427
9.4.9. TheReflectPackage .................................... 427
9.5. Exercises .................................................... 431
AppendixA. Epilogue ............................................ 435
AppendixB. TheDangersof SoftwarePatents .................. 437
AppendixC. SelectedBibliography .............................. 441
Index .............................................................. 443
Tables
2.1. Go’sKeywords .............................................. 52
2.2. Go’sPredefinedIdentifiers .................................. 52
2.3. BooleanandComparisonOperators .......................... 57
2.4. ArithmeticOperatorsApplicabletoAllBuilt-InNumbers ...... 59
2.5. Go’sIntegerTypesandRanges .............................. 60
2.6. ArithmeticOperatorsApplicableOnlytoBuilt-InIntegerTypes 60
2.7. Go’sFloating-PointTypes .................................... 64
2.8. TheMathPackage’sConstantsandFunctions#1 .............. 65
2.9. TheMathPackage’sConstantsandFunctions#2 .............. 66
2.10. TheMathPackage’sConstantsandFunctions#3 .............. 67
2.11. TheComplexMathPackage’sFunctions ...................... 71
3.1. Go’sStringandCharacterEscapes .......................... 84
3.2. StringOperations .......................................... 85
3.3. TheFmtPackage’sPrintFunctions .......................... 94
3.4. TheFmtPackage’sVerbs .................................... 95
3.5. TheFmtPackage’sVerbModifiers ............................ 96
3.6. TheStringsPackage’sFunctions#1 .......................... 108
3.7. TheStringsPackage’sFunctions#2 .......................... 109
3.8. TheStrconvPackage’sFunctions#1 .......................... 114
3.9. TheStrconvPackage’sFunctions#2 .......................... 115
3.10. TheUtf8Package’sFunctions ................................ 118
3.11. TheUnicodePackage’sFunctions ............................ 119
3.12. TheRegexpPackage’sFunctions ............................ 121
3.13. TheRegexpPackage’sEscapeSequences .................... 121
3.14. TheRegexpPackage’sCharacterClasses .................... 122
3.15. TheRegexpPackage’sZero-WidthAssertions ................ 122
3.16. TheRegexpPackage’sQuantifiers ............................ 123
3.17. TheRegexpPackage’sFlagsandGroups ...................... 123
3.18. The*regexp.RegexpType’sMethods#1 ...................... 124
3.19. The*regexp.RegexpType’sMethods#2 ...................... 125
4.1. SliceOperations ............................................ 151