book

Mastering Perl, 2nd Edition

by brian d foy

January 2014

Intermediate to advanced

400 pages

9h 23m

English

O'Reilly Media, Inc.

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Becoming a MasterWhat It Means to Be a MasterWho Should Read This BookHow to Read This BookWhat Should You Know Already?What I CoverWhat I Don’t CoverStructure of This BookConventions Used in This BookUsing Code ExamplesSafari® Books OnlineHow to Contact UsAcknowledgments
Readable Regexes, /x and (?#…)Global MatchingGlobal Match AnchorsRecursive Regular ExpressionsRepeating a SubpatternLookaroundsLookahead Assertions, (?=PATTERN) and (?!PATTERN)Positive lookahead assertionsNegative lookahead assertionsLookbehind Assertions, (?<!PATTERN) and (?<=PATTERN)Debugging Regular ExpressionsThe -D SwitchSummaryFurther Reading
Bad Data Can Ruin Your DayTaint CheckingWarnings Instead of Fatal ErrorsAutomatic Taint Modemod_perlTainted DataSide Effects of Taint CheckingUntainting DataIO::Handle::untaintHash KeysTaint::UtilChoosing Untainted Data with Tainted DataSymbolic ReferencesDefensive Database Programming with DBIList Forms of system and execThree-Argument opensysopenLimit Special PrivilegesSafe CompartmentsSafe LimitationsA Little FunSummaryFurther Reading
Before You Waste Too Much TimeThe Best Debugger in the WorldSafely Changing ModulesWrapping SubroutinesThe Perl DebuggerAlternative DebuggersUsing a Different Debugger with -dDevel::ptkdbDevel::ebugDevel::hdbIDE DebuggersEPICKomodoSummaryFurther Reading
Finding the CulpritThe General ApproachProfiling DBIOther DBI::Profile ReportsMaking It Even EasierSwitching DatabasesDevel::NYTProfWriting My Own ProfilerDevel::LineCounterProfiling Test SuitesDevel::CoverSummaryFurther Reading
Benchmarking TheoryBenchmarking TimeComparing CodeDon’t Turn Off Your Thinking CapIsolating the EnvironmentHandling OutliersMemory UseThe perlbench ToolSummaryFurther Reading
Good StyleperltidyDeobfuscationDe-encoding Hidden SourceUnparsing Code with B::DeparsePerl::CriticCreating My Own Perl::Critic PolicySummaryFurther Reading
Package and Lexical VariablesGetting the Package VersionThe Symbol TableTypeglobsAliasingFilehandle Arguments in Older CodeNaming Anonymous SubroutinesThe Easy WaySummaryFurther Reading
Subroutines as DataCreating and Replacing Named SubroutinesSymbolic ReferencesIterating Through Subroutine ListsProcessing PipelinesSelf-Referencing Anonymous SubroutinesMethod ListsSubroutines as ArgumentsAutoloaded MethodsHashes as ObjectsAutoSplitSummaryFurther Reading
Choosing the Right SolutionSending Patches to the AuthorLocal PatchesTaking Over a ModuleForkingStarting Over on My OwnReplacing Module PartsSubclassingAn ExtUtils::MakeMaker ExampleOther ExamplesWrapping SubroutinesSummaryFurther Reading

Things Not to DoCode in a Separate FileBetter WaysEnvironment VariablesSpecial Environment VariablesTurning on Extra OutputCommand-Line SwitchesThe -s SwitchGetopt ModulesGetopt::StdGetopt::LongConfiguration FilesConfigReader::SimpleConfig::IniFilesConfig::ScopedOther Configuration FormatsScripts with a Different NameInteractive and Noninteractive Programsperl’s ConfigDifferent Operating SystemsSummaryFurther Reading
Perl Error BasicsOperating System ErrorsChild Process ErrorsErrors Specific to the Operating SystemReporting Module ErrorsSeparation of ConcernsExceptionsevalMultiple Levels of diedie with a ReferencePropagating Objects with dieClobbering $@autodieReporting the CulpritCatching ExceptionsTry::TinyTryCatchPolymorphic Return ValuesSummaryFurther Reading
Recording Errors and Other InformationLog4perlSubroutine ArgumentsConfiguring Log4perlAdding my own informationPersistent ConfigurationLogging CategoriesCategories are hierarchicalOther Log::Log4perl FeaturesSummaryFurther Reading
Perl-Specific FormatspackFixed-Length RecordsUnpacking Binary FormatsData::DumperSimilar ModulesStorableFreezing DataStorable’s Security ProblemSerealDBM FilesdbmopenDBM::DeepPerl-Agnostic FormatsJSONYAMLYAML module variantsMessagePackSummaryFurther Reading
The Pod FormatDirectivesEncodingBody ElementsTranslating PodPod TranslatorsPod::Perldoc::ToTocPod::SimpleSubclassing Pod::SimplePod in Your Web ServerTesting PodChecking PodPod CoverageHiding and Ignoring FunctionsSummaryFurther Reading
Binary NumbersWriting in BinaryBit OperatorsUnary NOT (~)Bitwise AND (&)Binary OR (|)Exclusive OR (^)Left << and Right >> Shift OperatorsBit VectorsThe vec FunctionBit String StorageStoring DNAChecking PrimesKeeping Track of ThingsSummaryFurther Reading
They Look Like Normal VariablesAt the User LevelBehind the CurtainScalarsTie::CycleBounded IntegersSelf-Destructing ValuesArraysReinventing ArraysSomething a Bit More RealisticHashesFilehandlesSummaryFurther Reading
The main ThingBacking UpWho’s Calling?Testing the ProgramModules as TestsCreating a Program DistributionAdding to the ScriptDistributing the ProgramsSummaryFurther Reading
Perl BooksNon-Perl Books
My Philosophy of Problem-SolvingMy MethodSome Stupid Things I’ve Done and Still Do

Content preview from Mastering Perl, 2nd Edition

Appendix B. brian’s Guide to Solving Any Perl Problem

After several years of teaching Perl and helping other people solve their Perl problems, I wrote this guide, which shows how I think through a problem. It’s appeared on a couple of websites, and there are even several translations.

Some of the stuff I did unconsciously, and those are the hardest concepts to pass on to a new programmer. Now that this guide is available, other people can develop their own problem-solving skills. It might not solve all of your Perl problems, but it’s a good place to start.

My Philosophy of Problem-Solving

I believe in three things when it comes to programming, and even everything else I do. Starting with the right attitude can help you avoid various subconscious blocks that prevent you from seeing problems.

It is not personal

Forget about code ownership. You may think of yourself an artist, but even the Old Masters produced a lot of crap. Everybody’s code is crap, which means my code is crap and your code is crap. Learn to love that. When you have a problem, your first thought should be “Something is wrong with my crappy code.” That means you do not get to blame perl. It is not personal.

Forget about how you do things. If your way worked, you would not be reading this. That is not a bad thing; it’s just time to evolve. We’ve all been there.

Personal responsibility

If you have a problem with your program it is just that—your problem. You should do as much to solve it by yourself as you can. Remember, everyone ...