Many programmers code by instinct, relying on convenient habits or a
'style' they picked up early on. They aren't conscious of all the
choices they make, like how they format their source, the names they use
for variables, or the kinds of loops they use. They're focused entirely
on problems they're solving, solutions they're creating, and algorithms
they're implementing. So they write code in the way that seems natural,
that happens intuitively, and that feels good. But if you're serious about your profession, intuition isn't enough.
Perl Best Practices author Damian Conway explains that rules,
conventions, standards, and practices not only help programmers
communicate and coordinate with one another, they also provide a
reliable framework for thinking about problems, and a common language
for expressing solutions. This is especially critical in Perl, because
the language is designed to offer many ways to accomplish the same task,
and consequently it supports many incompatible dialects.
With a good dose of Aussie humor, Dr. Conway (familiar to many in the
Perl community) offers 256 guidelines on the art of coding to help you
write better Perl code--in fact, the best Perl code you possibly can.
The guidelines cover code layout, naming conventions, choice of data and
control structures, program decomposition, interface design and
implementation, modularity, object orientation, error handling, testing,
and debugging.
They're designed to work together to produce code that is clear, robust,
efficient, maintainable, and concise, but Dr. Conway doesn't pretend
that this is the one true universal and unequivocal set of best
practices. Instead, Perl Best Practices offers coherent and widely
applicable suggestions based on real-world experience of how code is
actually written, rather than on someone's ivory-tower theories on how
software ought to be created.
Most of all, Perl Best Practices offers guidelines that actually work,
and that many developers around the world are already using. Much like
Perl itself, these guidelines are about helping you to get your job
done, without getting in the way.
Praise for Perl Best Practices from Perl community members:
'As a manager of a large Perl project, I'd ensure that every member of my team has a copy of Perl Best Practices on their desk, and use it as the basis for an in-house style guide.' -- Randal Schwartz
'There are no more excuses for writing bad Perl programs. All levels of Perl programmer will be more productive after reading this book.' -- Peter Scott
'Perl Best Practices will be the next big important book in the evolution of Perl. The ideas and practices Damian lays down will help bring Perl out from under the embarrassing heading of 'scripting languages'. Many of us have known Perl is a real programming language, worthy of all the tasks normally delegated to Java and C++. With Perl Best Practices, Damian shows specifically how and why, so everyone else can see, too.' -- Andy Lester
'Damian's done what many thought impossible: show how to build large, maintainable Perl applications, while still letting Perl be the powerful, expressive language that programmers have loved for years.' -- Bill Odom
'Finally, a means to bring lasting order to the process and product of real Perl development teams.' -- Andrew Sundstrom
'Perl Best Practices provides a valuable education in how to write robust, maintainable Perl, and is a definitive citation source when coaching other programmers.' -- Bennett Todd
'I've been teaching Perl for years, and find the same question keeps being asked: Where can I find a reference for writing reusable, maintainable Perl code? Finally I have a decent answer.' -- Paul Fenwick
'At last a well researched, well thought-out, comprehensive guide to Perl style. Instead of each of us developing our own, we can learn good practices from one of Perl's most prolific and experienced authors. I recommend this book to anyone who prefers getting on with the job rather than going back and fixing errors caused by syntax and poor style issues.' -- Jacinta Richardson
'If you care about programming in any language read this book. Even if you don't intend to follow all of the practices, thinking through your style will improve it.' -- Steven Lembark
'The Perl community's best author is back with another outstanding book. There has never been a comprehensive reference on high quality Perl coding and style until Perl Best Practices. This book fills a large gap in every Perl bookshelf.' -- Uri Guttman
Table of Contents
Preface
1. Best Practices
Three Goals
This Book
Rehabiting
2. Code Layout
Bracketing
Keywords
Subroutines and Variables
Builtins
Keys and Indices
Operators
Semicolons
Commas
Line Lengths
Indentation
Tabs
Blocks
Chunking
Elses
Vertical Alignment
Breaking Long Lines
Non-Terminal Expressions
Breaking by Precedence
Assignments
Ternaries
Lists
Automated Layout
3. Naming Conventions
Identifiers
Booleans
Reference Variables
Arrays and Hashes
Underscores
Capitalization
Abbreviations
Ambiguous Abbreviations
Ambiguous Names
Utility Subroutines
4. Values and Expressions
String Delimiters
Empty Strings
Single-Character Strings
Escaped Characters
Constants
Leading Zeros
Long Numbers
Multiline Strings
Here Documents
Heredoc Indentation
Heredoc Terminators
Heredoc Quoters
Barewords
Fat Commas
Thin Commas
Low-Precedence Operators
Lists
List Membership
5. Variables
Lexical Variables
Package Variables
Localization
Initialization
Punctuation Variables
Localizing Punctuation Variables
Match Variables
Dollar-Underscore
Array Indices
Slicing
Slice Layout
Slice Factoring
6. Control Structures
If Blocks
Postfix Selectors
Other Postfix Modifiers
Negative Control Statements
C-Style Loops
Unnecessary Subscripting
Necessary Subscripting
Iterator Variables
Non-Lexical Loop Iterators
List Generation
List Selections
List Transformation
Complex Mappings
List Processing Side Effects
Multipart Selections
Value Switches
Tabular Ternaries
do-while Loops
Linear Coding
Distributed Control
Redoing
Loop Labels
7. Documentation
Types of Documentation
Boilerplates
Extended Boilerplates
Location
Contiguity
Position
Technical Documentation
Comments
Algorithmic Documentation
Elucidating Documentation
Defensive Documentation
Indicative Documentation
Discursive Documentation
Proofreading
8. Built-in Functions
Sorting
Reversing Lists
Reversing Scalars
Fixed-Width Data
Separated Data
Variable-Width Data
String Evaluations
Automating Sorts
Substrings
Hash Values
Globbing
Sleeping
Mapping and Grepping
Utilities
9. Subroutines
Call Syntax
Homonyms
Argument Lists
Named Arguments
Missing Arguments
Default Argument Values
Scalar Return Values
Contextual Return Values
Multi-Contextual Return Values
Prototypes
Implicit Returns
Returning Failure
10. I/O
Filehandles
Indirect Filehandles
Localizing Filehandles
Opening Cleanly
Error Checking
Cleanup
Input Loops
Line-Based Input
Simple Slurping
Power Slurping
Standard Input
Printing to Filehandles
Simple Prompting
Interactivity
Power Prompting
Progress Indicators
Automatic Progress Indicators
Autoflushing
11. References
Dereferencing
Braced References
Symbolic References
Cyclic References
12. Regular Expressions
Extended Formatting
Line Boundaries
String Boundaries
End of String
Matching Anything
Lazy Flags
Brace Delimiters
Other Delimiters
Metacharacters
Named Characters
Properties
Whitespace
Unconstrained Repetitions
Capturing Parentheses
Captured Values
Capture Variables
Piecewise Matching
Tabular Regexes
Constructing Regexes
Canned Regexes
Alternations
Factoring Alternations
Backtracking
String Comparisons
13. Error Handling
Exceptions
Builtin Failures
Contextual Failure
Systemic Failure
Recoverable Failure
Reporting Failure
Error Messages
Documenting Errors
OO Exceptions
Volatile Error Messages
Exception Hierarchies
Processing Exceptions
Exception Classes
Unpacking Exceptions
14. Command-Line Processing
Command-Line Structure
Command-Line Conventions
Meta-options
In-situ Arguments
Command-Line Processing
Interface Consistency
Interapplication Consistency
15. Objects
Using OO
Criteria
Pseudohashes
Restricted Hashes
Encapsulation
Constructors
Cloning
Destructors
Methods
Accessors
Lvalue Accessors
Indirect Objects
Class Interfaces
Operator Overloading
Coercions
16. Class Hierarchies
Inheritance
Objects
Blessing Objects
Constructor Arguments
Base Class Initialization
Construction and Destruction
Automating Class Hierarchies
Attribute Demolition
Attribute Building
Coercions
Cumulative Methods
Autoloading
17. Modules
Interfaces
Refactoring
Version Numbers
Version Requirements
Exporting
Declarative Exporting
Interface Variables
Creating Modules
The Standard Library
CPAN
18. Testing and Debugging
Test Cases
Modular Testing
Test Suites
Failure
What to Test
Debugging and Testing
Strictures
Warnings
Correctness
Overriding Strictures
The Debugger
Manual Debugging
Semi-Automatic Debugging
19. Miscellanea
Revision Control
Other Languages
Configuration Files
Formats
Ties
Cleverness
Encapsulated Cleverness
Benchmarking
Memory
Caching
Memoization
Caching for Optimization
Profiling
Enbugging
A. Essential Perl Best Practices
B. Perl Best Practices
C. Editor Configurations
D. Recommended Modules and Utilities
E. Bibliography
Index
