Index

Symbols

# (hash symbol), Writing in Binary
$! variable, Perl Error Basics, Operating System Errors
$0 variable, Scripts with a Different Name
$? variable, Perl Error Basics, Child Process Errors, Left << and Right >> Shift Operators
$@ variable, Perl Error Basics, eval–autodie
$_ variable, Safe Compartments, The Symbol Table
% (modulus) operator, Subroutines as Data
%! hash, Operating System Errors
& (AND) operator, Bitwise AND (&)–Bitwise AND (&)
(?!PATTERN) lookaheads, Negative lookahead assertions–Negative lookahead assertions
(?#...) sequence, Readable Regexes, /x and (?#…)
(?1) syntax, Repeating a Subpattern–Repeating a Subpattern
(?<!PATTERN) lookbehinds, Lookbehind Assertions, (?<!PATTERN) and (?<=PATTERN)
(?<=PATTERN) lookbehinds, Lookbehind Assertions, (?<!PATTERN) and (?<=PATTERN)
(?=PATTERN) lookaheads, Positive lookahead assertions–Positive lookahead assertions
*_ variable, Safe Compartments
// (defined-OR) operator, Turning on Extra Output
/x flag, Readable Regexes, /x and (?#…)
: (colon), JSON
<< (left shift) operator, Left << and Right >> Shift Operators
>> (right shift) operator, Left << and Right >> Shift Operators
@_ variable, Safe Compartments, The Symbol Table, Subroutines as Arguments
^ (exclusive OR) operator, Exclusive OR (^)–Exclusive OR (^)
| (OR) operator, Binary OR (|)–Binary OR (|)
|| (short circuit) operator, Turning on Extra Output
~ (NOT) operator, Unary NOT (~)

A

Aas, Gisle, Readable Regexes, /x and (?#…), The perlbench Tool

.al file, AutoSplit

aliasing variables, Aliasing–Aliasing

American Stance, Untainting Data

anchors, global match, Global Match Anchors–Global Match Anchors

AND (&) operator, Bitwise AND (&)–Bitwise AND (&)

anonymous subroutines

assigning to typeglobs, Creating and Replacing Named Subroutines–Creating and Replacing Named Subroutines, Autoloaded Methods
naming, Naming Anonymous Subroutines
self-referencing, Self-Referencing Anonymous Subroutines
storing in variables, Subroutines as Data–Subroutines as Data

appenders, Log4perl, Configuring Log4perl

arguments

open function and, Three-Argument open
subroutines and, Subroutines as Arguments–Subroutines as Arguments, Subroutine Arguments

@ARGV variable, Untainting Data, Don’t Turn Off Your Thinking Cap, Command-Line Switches

ARRAY variable type, Typeglobs, Aliasing, Arrays–Something a Bit More Realistic

AUTOLOAD subroutine

autoloaded methods, Autoloaded Methods
hiding and ignoring functions, Hiding and Ignoring Functions
naming anonymous subroutines, Naming Anonymous Subroutines
Safe compartments and, Safe Compartments

automatic taint model, Automatic Taint Mode

autosplitting modules, AutoSplit, Further Reading

B

\b anchor, Negative lookahead assertions, Lookbehind Assertions, (?<!PATTERN) and (?<=PATTERN)

Barr, Graham, Subroutines as Arguments–Subroutines as Arguments

BASH_ENV environment variable, Side Effects of Taint Checking

BEGIN blocks, Replacing Module Parts, Code in a Separate File

Belperchinov-Shabanski, Vladi, Further Reading

ben Jore, Joshua, Unparsing Code with B::Deparse

benchmarking Perl

benchmarking theory, Benchmarking Theory–Benchmarking Theory
comparing code, Comparing Code–Comparing Code
handling outliers, Handling Outliers–Handling Outliers
isolating the environment, Isolating the Environment–Isolating the Environment
measuring runtime, Benchmarking Time–Benchmarking Time
memory use, Memory Use–Memory Use
perlbench tool, The perlbench Tool–Summary
using your thinking cap, Don’t Turn Off Your Thinking Cap–Don’t Turn Off Your Thinking Cap

binary numbers, Binary Numbers–Writing in Binary

bit fundamentals

binary numbers, Binary Numbers–Writing in Binary
bit operators, Bit Operators–Left << and Right >> Shift Operators
bit vectors, Bit Vectors–Bit Vectors
vec function, The vec Function–Keeping Track of Things

bit operators

AND, Bitwise AND (&)–Bitwise AND (&)
C language and, Bit Operators
exclusive OR, Exclusive OR (^)–Exclusive OR (^)
left shift, Left << and Right >> Shift Operators
NOT, Unary NOT (~)
OR, Binary OR (|)–Binary OR (|)
right shift, Left << and Right >> Shift Operators

bit vectors, Bit Vectors–Bit Vectors, The vec Function–Keeping Track of Things

Bjarmason, Ævar Arnfjörð, Taint::Util

blacklisting, Untainting Data

bounded integers, Bounded Integers

Bowen, Rich, Pod in Your Web Server

Breyer, Steffen, Further Reading

Brocard, Léon, Devel::ebug

Bunce, Tim, The General Approach, Making It Even Easier, Further Reading, Further Reading

Burke, Sean, Other Examples, The Pod Format, Translating Pod, Pod in Your Web Server

byte, defined, Writing in Binary

C

/c flag, Global Match Anchors

caller function, Who’s Calling?

Carman, Michael, Lookbehind Assertions, (?<!PATTERN) and (?<=PATTERN), The -D Switch, Further Reading

Cavalletto, Matthew Simon, Freezing Data

CDPATH environment variable, Side Effects of Taint Checking

Ceglowski, Maciej, Further Reading

CERT (Computer Emergency Response Team), Further Reading

Champoux, Yanick, Sending Patches to the Author

character class shortcuts, Untainting Data

child process errors, Child Process Errors–Child Process Errors

$CHILD_ERROR variable, Perl Error Basics

${^CHILD_ERROR_NATIVE} variable, Perl Error Basics

chmod function, Binary Numbers, Bitwise AND (&)

Christiansen, Tom, Repeating a Subpattern

Clark, Nick, Further Reading

CLEAR tie method, Hashes

CLOSE tie method, Filehandles

CODE variable type, Typeglobs, Creating and Replacing Named Subroutines

colon (:), JSON

comma-adding pattern, The -D Switch

command-line switches, Command-Line Switches–Getopt::Long

COMMIT statement (SQL), Switching Databases

complement (~) operator, Unary NOT (~)

Computer Emergency Response Team (CERT), Further Reading

Configure program, perl’s Config

configuring Perl programs

command-line switches and, Command-Line Switches–Getopt::Long
Config module, perl’s Config–Summary
configuration files, Configuration Files–Other Configuration Formats
environment variables and, Better Ways–Turning on Extra Output
interactive and noninteractive programs, Interactive and Noninteractive Programs
Log::Log4perl module, Configuring Log4perl–Adding my own information
scripts with a different name, Scripts with a Different Name
things not to do, Things Not to Do–Code in a Separate File

constraints, Iterating Through Subroutine Lists

Conway, Damian, The -D Switch, Wrapping Subroutines, Perl::Critic, Further Reading, Wrapping Subroutines, Interactive and Noninteractive Programs

Cozens, Simon, Further Reading, Further Reading, Command-Line Switches

CPAN, Modifying and Jury-Rigging Modules–Starting Over on My Own, Distributing the Programs

croak function (Carp), Reporting the Culprit–Reporting the Culprit

Cross, Dave, Further Reading

Crow, Phil, Further Reading

=cut directive (Pod), Directives

D

-D switch, The -D Switch–The -D Switch

-d switch

Devel::ptkdb module and, Devel::ptkdb
Devel::SmallProf module and, Finding the Culprit
Devel::Trace module and, Using a Different Debugger with -d
Getopt::Std module and, Getopt::Std
usage examples, The Perl Debugger

data persistence

DBM files and, DBM Files–DBM::Deep
Perl-agnostic formats, Perl-Agnostic Formats–MessagePack
Perl-specific formats, Perl-Specific Formats–Similar Modules
Sereal protocol and, Sereal–Sereal
Storable module and, Storable–Storable’s Security Problem

databases

profiling, The General Approach–Making It Even Easier
switching, Switching Databases–Switching Databases

dbiprof tool, Making It Even Easier

DBI_PROFILE environment variable, Profiling DBI, Making It Even Easier

DBM files, DBM Files–DBM::Deep, Further Reading

dbmclose function, dbmopen

dbmopen function, dbmopen, Binary Numbers, They Look Like Normal Variables

DEBUG level error message, Log4perl

debugging

with alternative debuggers, Alternative Debuggers–Devel::hdb, My Method
with IDE debuggers, IDE Debuggers–Komodo
Log::Log4perl module and, Log4perl
with print statements, The Best Debugger in the World, Turning on Extra Output
with Perl debugger, The Perl Debugger
regular expressions, Debugging Regular Expressions–The -D Switch
safely changing modules, Safely Changing Modules
with strict and warnings, Before You Waste Too Much Time
warn statements and, The Best Debugger in the World
wrapping subroutines, Wrapping Subroutines–Wrapping Subroutines

(?(DEFINE)...) syntax, Repeating a Subpattern–Repeating a Subpattern

defined-OR (//) operator, Turning on Extra Output

DELETE tie method, Hashes

Descartes, Alligator, Further Reading

DESTROY method, Safe Compartments, Clobbering $@, Behind the Curtain

detecting errors (see error handling)

die function

$@ variable and, Clobbering $@–autodie
eval function and, eval
exit function and, Child Process Errors
multiple levels of, Multiple Levels of die
perlcritic command and, Perl::Critic
propagating objects with, Propagating Objects with die–Propagating Objects with die
with a reference, die with a Reference
reporting errors, Reporting the Culprit

diff command, Sending Patches to the Author, Further Reading

directives (Pod), Directives–Encoding

distributions (program)

creating, Creating a Program Distribution–Distributing the Programs
uploading, Distributing the Programs

DNA

storing, Storing DNA
writing in binary, Writing in Binary

do function, Data::Dumper

Dominus, Mark Jason, Untainting Data, Further Reading, Further Reading, Further Reading

dynamic subroutines, Dynamic Subroutines–Further Reading

E

-e switch, The Perl Debugger

$^E variable, Perl Error Basics, Errors Specific to the Operating System

encoding

hidden source code, De-encoding Hidden Source–De-encoding Hidden Source
POD considerations, Encoding

=encoding directive (Pod), Encoding

END blocks, The General Approach, Devel::LineCounter, Child Process Errors

__END__ token, AutoSplit

ENV environment variable, Side Effects of Taint Checking

%ENV hash, Taint Checking, Tainted Data, Environment Variables

environment variables, Environment Variables–Turning on Extra Output, Turning on Extra Output

environment, isolating, Isolating the Environment–Isolating the Environment

EPIC (Eclipse Perl Integration) debugger, EPIC

$ERRNO variable, Perl Error Basics

error handling

child process errors, Child Process Errors–Child Process Errors
exceptions and, Exceptions–autodie, Catching Exceptions–TryCatch
operating systems, Operating System Errors–Operating System Errors, Errors Specific to the Operating System
placeholders for message patterns, Configuring Log4perl
polymorphic return values and, Polymorphic Return Values
recording, Recording Errors and Other Information
reporting errors, Reporting the Culprit–Reporting the Culprit
reporting module errors, Reporting Module Errors–Separation of Concerns
special reporting variables, Perl Error Basics

ERROR level error message, Log4perl

eval function, eval, Clobbering $@–autodie, Data::Dumper

$EVAL_ERROR variable, Perl Error Basics

Evans, Paul, Subroutines as Arguments

exceptions

catching, Catching Exceptions–TryCatch
throwing, Exceptions–autodie

exclusive OR (^) operator, Exclusive OR (^)–Exclusive OR (^)

exec function, List Forms of system and exec

EXISTS tie method, Hashes

exit function, Child Process Errors

@EXPORT variable, Creating and Replacing Named Subroutines

@EXPORT_OK variable, Creating and Replacing Named Subroutines

$EXTENDED_OS_ERROR variable, Perl Error Basics

F

FATAL level error message, Log4perl

FETCH tie method, Tie::Cycle–Self-Destructing Values, Hashes

-file switch, Getopt::Long

filehandles

arguments in older code, Filehandle Arguments in Older Code
tied variables and, Filehandles

flock function, Binary OR (|)

Foley, Richard, The Perl Debugger, Further Reading

forking, Forking

formats (Perl-agnostic)

JSON, Repeating a Subpattern, JSON–JSON, Further Reading
MessagePack, MessagePack
YAML, Other Configuration Formats, YAML–YAML module variants, Further Reading

formats (Perl-specific)

Data::Dumper module and, Data::Dumper–Similar Modules
fixed-length records, Fixed-Length Records
pack function and, pack
Sereal protocol and, Sereal–Sereal, Further Reading
unpacking binary, Unpacking Binary Formats

formats (Pod), The Pod Format–Body Elements

freezing data, Freezing Data–Freezing Data

Friedl, Jeffrey, Lookbehind Assertions, (?<!PATTERN) and (?<=PATTERN), Further Reading

G

\G anchor, Global Match Anchors, Lookbehind Assertions, (?<!PATTERN) and (?<=PATTERN)
/g flag, Global Matching
-g switch, Getopt::Std
Garcia-Suarez, Rafaël, Further Reading
glob function, Don’t Turn Off Your Thinking Cap–Don’t Turn Off Your Thinking Cap
GLOB variable type, Typeglobs, Filehandle Arguments in Older Code
global matching, Global Matching–Global Match Anchors
-gnu switch (perltidy), perltidy
Goess, Kevin, Log4perl
grep utility, Iterating Through Subroutine Lists, Subroutines as Arguments

H

HARNESS_PERL_SWITCHES environment variable, Devel::Cover

hash keys

accessing values, Hashes as Objects
untainting data and, Hash Keys

hash symbol (#), Writing in Binary

HASH variable type, Typeglobs, Hashes–Filehandles

=head directive (Pod), Pod::Perldoc::ToToc, Pod::Simple

hex function, Writing in Binary

Hoare, Tony, Benchmarking Perl

Hoffman, Paul, Hashes as Objects

.htaccess file, Environment Variables

-html switch (perltidy), perltidy

Huckaby, Joe, DBM::Deep

%main:: symbol table, The Symbol Table

Makefile file, An ExtUtils::MakeMaker Example

Maki, Eric, Keeping Track of Things, Further Reading

map function, Don’t Turn Off Your Thinking Cap, Subroutines as Arguments

Mapped Diagnostic Context (MDC), Adding my own information

MATCH blocks, Global Match Anchors

McAdams, Josh, Further Reading

MDC (Mapped Diagnostic Context), Adding my own information

measuring performance (see benchmarking Perl)

memory use, benchmarking and, Memory Use–Memory Use

Menon-Sen, Abhijit, Further Reading

messages

placeholders for, Configuring Log4perl
printing, Taint Checking

metacharacters, List Forms of system and exec

method lists, Method Lists

mkdir function, Binary Numbers

%module hash, Different Operating Systems

modules

associating hashes with, They Look Like Normal Variables
autosplitting, AutoSplit, Further Reading
as programs, Modules as Programs–Further Reading
replacing parts, Replacing Module Parts–Replacing Module Parts
reporting errors, Reporting Module Errors–Separation of Concerns, Reporting the Culprit–Reporting the Culprit
safely changing, Safely Changing Modules
solutions for fixing, Choosing the Right Solution–Starting Over on My Own
subclassing, Subclassing–Other Examples, Subclassing Pod::Simple
taking of maintenance of, Taking Over a Module
as tests, Modules as Tests–Modules as Tests
wrapping subroutines, Wrapping Subroutines–Wrapping Subroutines

modulus (%) operator, Subroutines as Data

Müller, Steffen, Handling Outliers, Further Reading, Further Reading

N

N directive, Subclassing Pod::Simple
named subroutines, Creating and Replacing Named Subroutines–Creating and Replacing Named Subroutines
naming anonymous subroutines, Naming Anonymous Subroutines
NDC (Nested Diagnostic Context), Adding my own information
negative lookahead assertions, Negative lookahead assertions–Negative lookahead assertions
negative lookbehind assertions, Lookbehind Assertions, (?<!PATTERN) and (?<=PATTERN)–Lookbehind Assertions, (?<!PATTERN) and (?<=PATTERN)
Nested Diagnostic Context (NDC), Adding my own information
NEXTKEY tie method, Hashes
noninteractive programs, Interactive and Noninteractive Programs
NOT (~) operator, Unary NOT (~)
nroff program, Pod Translators
nybble, defined, Writing in Binary

O

-o switch, Getopt::Std

$^O variable, Different Operating Systems

obfuscating code, Deobfuscation–Unparsing Code with B::Deparse

objects

hashes as, Hashes as Objects
propagating with die, Propagating Objects with die–Propagating Objects with die
tied variables and, Behind the Curtain

oct function, Writing in Binary

OPEN blocks, Operating System Errors

open function

appenders and, Log4perl
autodie module and, autodie
operating system errors, Operating System Errors
three-argument, Three-Argument open

operating systems

configuring programs, Different Operating Systems
error handling, Operating System Errors–Operating System Errors, Errors Specific to the Operating System
interacting with functions, Bad Data Can Ruin Your Day

OR (|) operator, Binary OR (|)–Binary OR (|)

$OS_ERROR variable, Perl Error Basics

outliers, benchmarking and, Handling Outliers–Handling Outliers

P

pack function, pack

__PACKAGE__ directive, die with a Reference, Logging Categories

package variables, Package and Lexical Variables–Getting the Package Version

(?PARNO) syntax, Repeating a Subpattern

patch program, Sending Patches to the Author, Further Reading

patches, Sending Patches to the Author–Sending Patches to the Author

PATH environment variable, Taint Checking

patterns

comma-adding, The -D Switch
placeholders for messages, Configuring Log4perl
repeating subpatterns, Repeating a Subpattern–Repeating a Subpattern

PAUSE (Perl Authors Upload Server), Taking Over a Module–Forking

Perl Authors Upload Server (PAUSE), Taking Over a Module–Forking

Perl debugger, The Perl Debugger

PERL5DB environment variable, Finding the Culprit

PERL5LIB environment variable, Side Effects of Taint Checking, Safely Changing Modules, Special Environment Variables

PERL5OPT environment variable, Finding the Culprit, Special Environment Variables

perlapi documentation, Further Reading

perlbench tool, The perlbench Tool–Summary

perlboot documentation, Further Reading

perlcritic command, Perl::Critic–Perl::Critic

perldata documentation, Further Reading

perldebguts documentation, The -D Switch, Further Reading, Memory Use

perldebug documentation, The Perl Debugger

perldoc command, Pod Translators–Pod Translators, My Method

perldoc documentation, The main Thing

perlfunc documentation, Further Reading, Further Reading, Further Reading

perlmod documentation, Further Reading

perlop documentation, Further Reading

perlopentut documentation, Further Reading

perlpodspec documentation, The Pod Format

perlport documentation, Further Reading

perlre documentation, Further Reading

perlref documentation, Further Reading

perlreftut documentation, Further Reading

perlreref documentation, Further Reading

perlretut documentation, Further Reading

perlrun documentation, Further Reading

perlsec documentation, Further Reading

perlstyle documentation, perltidy, Further Reading

perlsub documentation, Further Reading, Subroutines as Arguments

PerlSwitches directive, mod_perl

PerlTaintCheck directive, mod_perl

perltidy program, perltidy–perltidy, Further Reading

perltie documentation, Arrays

perlvar documentation, Perl Error Basics

Pike, Rob, Further Reading

pipelines, processing, Processing Pipelines

POD (Plain Old Documentation)

format supporting, The Pod Format–Body Elements
testing, Testing Pod–Hiding and Ignoring Functions
translating, Translating Pod–Pod in Your Web Server

podchecker program, Checking Pod

polymorphic return values, Polymorphic Return Values

pos function, Global Matching

positive lookahead assertions, Positive lookahead assertions–Positive lookahead assertions

positive lookbehind assertions, Lookbehind Assertions, (?<!PATTERN) and (?<=PATTERN)–Lookbehind Assertions, (?<!PATTERN) and (?<=PATTERN)

prime numbers, checking, Checking Primes

print function

debugging with, The Best Debugger in the World, Turning on Extra Output
interactive programs and, Interactive and Noninteractive Programs
tied variables and, Filehandles

PRINT tie method, Filehandles

printf function, Writing in Binary, Filehandles

PRINTF tie method, Filehandles

printing messages, Taint Checking

problem-solving guide, brian’s Guide to Solving Any Perl Problem

--profile switch, Perl::Critic

profiling Perl

Devel::NYTProf module and, Devel::NYTProf
finding the culprit, Finding the Culprit–Finding the Culprit
general approach, The General Approach–The General Approach
profiling DBI, Profiling DBI–Switching Databases
profiling test suites, Profiling Test Suites–Summary
writing profilers, Writing My Own Profiler–Devel::LineCounter

Prussian Stance, Untainting Data

Q

qr function, Readable Regexes, /x and (?#…)

R

(?R) syntax, Repeating a Subpattern

Rabbitson, Peter, Further Reading

Randal, Allison, Pod::Simple, Subclassing Pod::Simple, Further Reading

Ray, Randy, Further Reading

READLINE tie method, Filehandles

recursive regular expressions, Recursive Regular Expressions–Repeating a Subpattern

regular expressions

debugging, Debugging Regular Expressions–The -D Switch
global matching, Global Matching–Global Match Anchors
lookarounds, Lookarounds–Lookbehind Assertions, (?<!PATTERN) and (?<=PATTERN)
readable, Readable Regexes, /x and (?#…)–Readable Regexes, /x and (?#…)
recursive, Recursive Regular Expressions–Repeating a Subpattern

release utility, Distributing the Programs

repeating subpatterns, Repeating a Subpattern–Repeating a Subpattern

REPL program example, Safe Compartments, Subroutines as Data

reporting errors (see error handling)

require function, Data::Dumper, Modules as Tests

return values

error handling, Separation of Concerns–Separation of Concerns
polymorphic, Polymorphic Return Values

Reverse Polish Notation, Subroutines as Data

reverse-engineering Perl, De-encoding Hidden Source–De-encoding Hidden Source

RFC 4627, Further Reading

right shift (>>) operator, Left << and Right >> Shift Operators

Rolsky, Dave, Further Reading, Recording Errors and Other Information

ROT-13 cipher, De-encoding Hidden Source–De-encoding Hidden Source

ROT-255 cipher, De-encoding Hidden Source

runtime, measuring, Benchmarking Time–Benchmarking Time

S

-s switch, Command-Line Switches–The -s Switch

scalar values (SVs), Hash Keys

SCALAR variable type, Typeglobs, Aliasing, Scalars–Self-Destructing Values

Schilli, Michael, Recording Errors and Other Information, Further Reading

Schwartz, Randal L., Repeating a Subpattern, Further Reading, Further Reading, Further Reading, Further Reading, Further Reading, Further Reading

Schwartzian Transform, Don’t Turn Off Your Thinking Cap–Don’t Turn Off Your Thinking Cap

scope, lexical variables and, Package and Lexical Variables–Getting the Package Version, Further Reading

Scott, Peter, Further Reading

scriptdist program, Creating a Program Distribution

security, Storable module and, Storable’s Security Problem–Storable’s Security Problem

seek function, Fixed-Length Records

self-destructing values, Self-Destructing Values

self-referencing anonymous subroutines, Self-Referencing Anonymous Subroutines

setuid flag, Binary Numbers

Shankar, Arun Udaya, Further Reading

short circuit (||) operator, Turning on Extra Output

Signes, Ricardo, Perl::Critic

Siminov, Kirill, YAML module variants

Simões, Alberto, Further Reading

sleep program (Unix), Benchmarking Time

Software Engineering Institute, Further Reading

special privileges, Limit Special Privileges

splice function, Reinventing Arrays

sprintf function, Configuring Log4perl, pack, Writing in Binary

SQLLite, Switching Databases

Starsinic, Kurt, Distributing the Programs

stashes, The Symbol Table, The Easy Way

STDERR filehandle, Filehandle Arguments in Older Code, Recording Errors and Other Information, Log4perl

STDIN filehandle, Filehandle Arguments in Older Code, Interactive and Noninteractive Programs

STDOUT filehandle, Filehandle Arguments in Older Code, Interactive and Noninteractive Programs

STORE tie method, Tie::Cycle–Self-Destructing Values, Hashes

strings (bit storage), Bit String Storage–Bit String Storage

__SUB__ token, Self-Referencing Anonymous Subroutines

subclassing modules, Subclassing–Other Examples, Subclassing Pod::Simple

subpatterns, repeating, Repeating a Subpattern–Repeating a Subpattern

subroutines

anonymous, Naming Anonymous Subroutines, Creating and Replacing Named Subroutines–Creating and Replacing Named Subroutines, Self-Referencing Anonymous Subroutines, Autoloaded Methods
arguments and, Subroutines as Arguments–Subroutines as Arguments, Subroutine Arguments
autoloaded methods and, Autoloaded Methods–AutoSplit
as data, Subroutines as Data–Subroutines as Data
dynamic, Dynamic Subroutines–Further Reading
iterating through lists, Iterating Through Subroutine Lists–Iterating Through Subroutine Lists
method lists and, Method Lists
named, Creating and Replacing Named Subroutines–Creating and Replacing Named Subroutines
processing pipelines, Processing Pipelines
symbolic references, Symbolic References–Symbolic References
wrapping, Wrapping Subroutines–Wrapping Subroutines, Wrapping Subroutines–Wrapping Subroutines

substr function, Bit Vectors, Reinventing Arrays

Sudoku example, Keeping Track of Things

SVs (scalar values), Hash Keys

symbol tables

aliasing variables and, Aliasing–Aliasing
filehandle arguments in older code, Filehandle Arguments in Older Code
manipulating easily, The Easy Way
package variables and, Package and Lexical Variables–Getting the Package Version
subroutines and, Naming Anonymous Subroutines, Creating and Replacing Named Subroutines
typeglobs and, Typeglobs–Typeglobs
usage overview, The Symbol Table–The Symbol Table

symbolic references, Symbolic References–Symbolic References, Symbolic References–Symbolic References

sysopen function, sysopen, Binary OR (|)

system function, List Forms of system and exec, Benchmarking Time, Child Process Errors, Left << and Right >> Shift Operators

T

-T switch, Taint Checking–Warnings Instead of Fatal Errors

-t switch, Warnings Instead of Fatal Errors

taint checking

automatic taint mode, Automatic Taint Mode
mod_perl module, mod_perl
setting up, Taint Checking–Taint Checking
side effects of, Side Effects of Taint Checking
tainted data, Tainted Data
untainting data and, Untainting Data–Symbolic References
warnings instead of fatal errors, Warnings Instead of Fatal Errors

${^TAINT} variable, Warnings Instead of Fatal Errors

test suites, profiling, Profiling Test Suites–Summary

-test switch, Devel::Cover

testing POD

hiding and ignoring functions, Hiding and Ignoring Functions
Pod::Checker module and, Checking Pod
Pod::Coverage module and, Pod Coverage–Pod Coverage

testing programs, Testing the Program–Modules as Tests

Thalhammer, Jeffrey, Perl::Critic

tie function, They Look Like Normal Variables–Behind the Curtain, Arrays, Filehandles

tied variables

arrays and, Arrays–Something a Bit More Realistic
filehandles and, Filehandles
hashes and, Hashes–Filehandles
objects and, Behind the Curtain
scalars and, Scalars–Self-Destructing Values
usage overview, They Look Like Normal Variables–At the User Level

TIESCALAR method, Behind the Curtain–Self-Destructing Values

time program (Unix), Benchmarking Time

time, benchmarking, Benchmarking Time–Benchmarking Time

times function (C), Benchmarking Time

times function (Perl), Benchmarking Time

timethese function (Benchmark), Comparing Code–Comparing Code

Torkington, Nathan, Further Reading

TRACE level error message, Log4perl

translating POD, Translating Pod–Pod in Your Web Server

Tregar, Sam, Making It Even Easier

typeglobs

aliasing variables and, Aliasing–Aliasing
assigning anonymous subroutines to, Creating and Replacing Named Subroutines–Creating and Replacing Named Subroutines, Autoloaded Methods
filehandle references to, Filehandle Arguments in Older Code
manipulating easily, The Easy Way
naming anonymous subroutines, Naming Anonymous Subroutines
package variables and, Package and Lexical Variables–Getting the Package Version
symbol tables and, Typeglobs–Typeglobs

U

-U switch, Warnings Instead of Fatal Errors

unary NOT (~) operator, Unary NOT (~)

unpack function, pack, Unpacking Binary Formats

unparsing code, Unparsing Code with B::Deparse–Unparsing Code with B::Deparse

unshift function, Behind the Curtain

untainting data

choosing with tainted data, Choosing Untainted Data with Tainted Data
hash keys, Hash Keys
IO::Handle module, IO::Handle::untaint
symbolic references, Symbolic References–Symbolic References
taint checking and, Untainting Data–Untainting Data
Taint::Util module, Taint::Util

use function

data persistence and, Data::Dumper
debugging and, Using a Different Debugger with -d
modules as tests, Modules as Tests
Safe compartments and, Safe Compartments

V

variables

aliasing, Aliasing–Aliasing
environment, Environment Variables–Turning on Extra Output, Turning on Extra Output
lexical, Package and Lexical Variables–Getting the Package Version
package, Package and Lexical Variables–Getting the Package Version
storing anonymous subroutines in, Subroutines as Data–Subroutines as Data
tied, The Magic of Tied Variables–Further Reading
types of, Typeglobs

vec function, The vec Function–Keeping Track of Things

-verbose switch, Getopt::Long

$!{VMSERR} variable, Errors Specific to the Operating System

W

\W character class shortcut, Untainting Data
\w character class shortcut, Untainting Data
-w switch, My Method
wait function, Left << and Right >> Shift Operators
Wall, Larry, Further Reading
Wardley, Andy, Reporting Module Errors
WARN level error message, Log4perl
warn statements, The Best Debugger in the World, Reporting the Culprit
web servers, using POD, Pod in Your Web Server
whitelisting, Untainting Data
Wiles, Frank, Further Reading
wrapping subroutines, Wrapping Subroutines–Wrapping Subroutines, Wrapping Subroutines–Wrapping Subroutines
Wright, Ed, Further Reading

Y

YAML (YAML Ain’t Markup Language), Other Configuration Formats, YAML–YAML module variants, Further Reading