Conway - Perl Best Practices

, Best Practices , explains why it might be worth reassessing your current coding practices. It discusses how coding styles are evolved, and sets out three broad criteria against which any existing or proposed coding practice can be assessed. The chapter also explains why good coding habits matter and suggests how they can be developed.

, Code Layout , tackles the many contentious issues of code layout. It suggests how to set out block delimiters; how to visually distinguish built-ins and keywords from subroutines and variables; where to place operators, terminators, delimiters, and other punctuation; how to improve readability by the consistent use of whitespace; the optimal width for code lines and block indents; how to set out lists of values; and where to break long expressions. It concludes by recommending a convenient tool that automates most of these layout tasks.

, Naming Conventions , presents a series of guidelines that can help you choose more descriptive names for variables, subroutines, and namespaces. It also demonstrates how the various components of a consistent naming scheme can work together to improve the overall maintainability of code, both by making it more readable and by reducing the need for deobfuscatory comments.

, Values and Expressions , provides a simple set of rules that can help you avoid common pitfalls when creating character strings, numbers, and lists. Topics include how to avoid unintended variable interpolation (and non-interpolation), reliable and readable approaches to nonprintable characters, defining constants, avoiding barewords, and taming heredocs, commas, long numbers, and lists.

, Variables , explores a robust approach to using variables. It explains the inherent drawbacks of package or punctuation variables, suggesting safer alternatives where possible, and safer practices where there are no alternatives. The second half of the chapter presents several efficient and maintainable techniques of handling data in arrays and hashes using the "container slicing" mechanism.

, Control Structures , examines Perl's rich variety of control structures, encouraging the use of those that are easier to maintain, less error-prone, or more efficient. The chapter provides a set of simple guidelines for deciding which of for, while, or map is most appropriate for a given task. The effective use of iterator variables is also discussed, including the common case of needing to iterate hash entries by key and value simultaneously.

, Documentation , suggests a series of techniques that can make documenting your code less tedious, and therefore more likely. It advocates a template-based approach to both user and technical documentation, and discusses when, where, and how to write useful and accurate comments.

, Built-in Functions , discusses better ways of using some of Perl's most popular built-in functions, including sort, reverse, scalar, eval, unpack, split, substr, values, select, sleep, map, and grep. It also summarizes the many other useful "non-built-in" builtins provided by two modules from the standard Perl distribution and one from CPAN.

, Subroutines , describes efficient and maintainable ways to write subroutines in Perl, including the use of positional, named, and optional arguments, argument validation and defaults, safe calling and return conventions, predictable return values in various contexts, and why subroutine prototypes and implicit returns should be avoided.

, I/O , explains how to open and close files reliably, when to use line-based input, how to correctly detect interactive applications, the importance of prompting, and how best to provide feedback to users during long non-interactive tasks.