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# Introduction

Introduction -- What Config can do

## Introduction

Config helps you manipulate your configuration whether they are stored in XML files, PHP arrays or other kind of datasources. It supports these features:

- Parse different configuration formats.

- Manipulate sections, directives, comments, blanks the way you want.

- Write them back to a datasource in your preferred format.

The Config object acts as a container for other Config_Container objects. It doesn't do much but makes handling IO operations easier. It contains the root Config_Container object which in turn contains a child Config_Container object. Config_Container objects store references to their parent and have an array of children. This structure makes it easy to access the different containers and their contents.

A Config_Container object can be of different type:

- Section: a section contains other Config_Container objects.

- Directive: a directive does not contain any other object but has content and a name. See them as key-value pairs.

- Comment: just like directives, comments have content but they don't have a name. They are rendered in a special way according to the configuration type you choosed.

- Blank: they don't have neither content or name but are used to indicate blank lines if your renderer uses them.

When using the Config package, most of the work is done with Config_Container objects.

Example 31-1. An example that will create a new Config_Container
    // initialize a Config_Container object

    require_once('Config.php');
    $conf =& new Config_Container('section', 'conf');
    $conf_DB =& $conf->createSection('DB');
    $conf_DB->createDirective('type', 'mysql');
    $conf_DB->createDirective('host', 'localhost');
    $conf_DB->createDirective('user', 'root');
    $conf_DB->createDirective('pass', 'root');

    // set this container as our root container child in Config

    $config = new Config();
    $config->setRoot($conf);

    // write the container to a php array

    $config->writeConfig('/tmp/config_test.php', 'phparray',
                         array('name' => 'test'));

    // print the content of our conf section to screen

    echo $conf->toString('phparray', array('name' => 'test'));

The above example illustrates how Config and Config_Container can interact. There are other ways. You could have for example first created the Config object and then used $config->getRoot() to add sections and directives to the returned object reference.

Example 31-2. Reading configuration from an XML file
    require_once 'Config.php';

    $conf = new Config;
    $root =& $conf->parseConfig('config.xml', 'XML');

    if (PEAR::isError($root)) {
        die('Error while reading configuration: ' . $root->getMessage());
    }

    $settings = $root->toArray();

    printf('User settings: <a href="%s">%s %s</a>',
           $settings['root']['conf']['www'],
           $settings['root']['conf']['firstname'],
           $settings['root']['conf']['lastname']
           );
In this example the XML file `config.xml` looks like this:
    <?xml version="1.0" encoding="UTF-8"?>

    <conf>
      <firstname>John</firstname>
      <lastname>Doe</lastname>

      <www>http://example.com/</www>
    </conf>

For more information, DevShed has a great tutorial about the Config package.

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