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Unit 11: Directories and Files

You should follow three principles on including files: Notes
1. Only use include_once or require_once. Rule number one is to always use require_once or
include_once to include PEAR code. If you use require, your script will likely die because
of redefinition errors (or it will die sometime in the future).
2. Determine the correlation between classes and file names. PEAR uses the one-class-per-file
principle, with the intention that it should be trivial to generate the required file name
from the class name. Replace underscores with the directory separator character, append.
php, and you’re finished. Here are some examples:

Class Name File Name

PEAR PEAR.php
XML_Parser XML/Parser.php

HTML_Quickform_textarea HTML/QuickForm/textarea.php
Case is significant here because UNIX file systems are case-sensitive.

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12.6 Building Packages 411

3. Encapsulate includes. Each file should use includes to express clearly which class it depends
on from other packages.

Scan Directories with PHP’s Directory Iterators
O ne of php5’s most interesting new features is the addition of iterators, a collection

of readmade interfaces designed to help in navigating and processing hierarchical
data structures. These Iterators signficantly reduce the amount of code required
to process an XML document tree or a file collection. A number of Iterators are available,
including the Array Iteratior, CachingIterator, Limit Iterator, Racursive Iterator, Simple
XMLIterator and Directory Iterator.

Processing a Single-level Directory

Let’s begin with something simple: processing a single-level directory. Type (or copy) the
following script (Listing A), altering the directory path to reflect your local configuration:

Listing A
<? php

$it = new DirectoryIterator (“/tmp/mystuff’);

foreach $it as $file) {
if (!$ it-> is Dot ()) {
Contd...

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