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| <td><h1>Code Igniter User Guide Version 1.4.0</h1></td> | |
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| <a href="http://www.codeigniter.com/">Code Igniter Home</a> › | |
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| Creating Libraries | |
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| <h1>Creating Libraries</h1> | |
| <p>When we use the term "Libraries" we are normally referring to the classes that are located in the <kbd>libraries</kbd> | |
| directory and described in the Class Reference of this user guide. In this case, however, we will instead describe how you can create your own libraries within | |
| your <dfn>application</dfn> directory in order to maintain separation between your local resources and the global framework resources.</p> | |
| <h2>Storage</h2> | |
| <p>In order for your libraries to be stored in your <kbd>application</kbd> folder you will need to create two directories in which to store them:</p> | |
| <ul> | |
| <li>application/<dfn>init</dfn></li> | |
| <li>application/<dfn>libraries</dfn></li> | |
| </ul> | |
| <h2>Anatomy of a Library</h2> | |
| <p>A class library consists of two components:</p> | |
| <ol> | |
| <li>An <kbd>init</kbd> file.</li> | |
| <li>A <kbd>class</kbd> file.</li> | |
| </ol> | |
| <h2>The Init File</h2> | |
| <p>An <kbd>init</kbd> file a small initialization file corresponding to each of your classes. The purpose of this file is to | |
| instantiate a particular class. Each init file must be named identically to your class file name, adding the "init_" prefix. For example, if your | |
| class is named <dfn>myclass.php</dfn> your init file will be named:</p> | |
| <code>init_myclass.php</code> | |
| <p>Within your init file you will place your initialization code. Here's an example of such code, using an imaginary class named <kbd>Myclass</kbd>:</p> | |
| <code><?php if (!defined('BASEPATH')) exit('No direct script access allowed');<br /> | |
| <br /> | |
| if ( ! class_exists('<kbd>Myclass</kbd>'))<br /> | |
| {<br /> | |
| require_once(APPPATH.'libraries/<kbd>Myclass</kbd>'.EXT);<br /> | |
| }<br /> | |
| <br /> | |
| $obj =& get_instance();<br /> | |
| $obj-><kbd>myclass</kbd> = new <kbd>Myclass();</kbd><br /> | |
| $obj->ci_is_loaded[] = '<kbd>myclass</kbd>';<br /> | |
| <br /> | |
| ?></code> | |
| <h2>The Class File</h2> | |
| <p>Your class file itself will be placed inside your <dfn>libraries</dfn> directory:</p> | |
| <code>application/libraries/<dfn>myclass.php</dfn></code> | |
| <p>The class will have this basic prototype:</p> | |
| <code><?php if (!defined('BASEPATH')) exit('No direct script access allowed');<br /> | |
| <br /> | |
| class Myclass {<br /> | |
| <br /> | |
| }<br /> | |
| ?></code> | |
| <h2>Naming Conventions</h2> | |
| <ul> | |
| <li>All file names must be in lowercase: myclass.php and init_myclass.php</li> | |
| <li>Class names must be capitalize: class Myclass</li> | |
| </ul> | |
| <h2>Using Your Class</h2> | |
| <p>From within any of your <a href="controllers.html">Controller</a> classes you can initialize your class using the standard:</p> | |
| <code>$this->load->library('<kbd>myclass</kbd>');</code> | |
| <p>Once loaded you can access your class using:</p> | |
| <code>$this-><kbd>myclass</kbd>->function();</code> | |
| <p>Note: In your init file you can define the object variable name.</p> | |
| <h2>Passing Parameters Your Class</h2> | |
| <p>In the library loading function you can pass data via the second parameter and it will be available to your initialization file:</p> | |
| <code> | |
| $params = array('type' => 'large', 'color' => 'red');<br /> | |
| <br /> | |
| $this->load->library('myclass', <kbd>$params</kbd>);</code> | |
| <p>Parameters will be accessible using a variable called <kbd>$params</kbd>. By default this variable is set to FALSE.</p> | |
| <h2>Utilizing Code Igniter Resources within Your Library</h2> | |
| <p>To access Code Igniter's native resources within your library use the <kbd>get_instance()</kbd> function. | |
| This function returns the Code Igniter super object.</p> | |
| <p>Normally, to call any of the available Code Igniter functions requires you to use the <kbd>$this</kbd> construct:</p> | |
| <code> | |
| <strong>$this</strong>->load->helper('url');<br /> | |
| <strong>$this</strong>->load->library('session');<br /> | |
| <strong>$this</strong>->config->item('base_url');<br /> | |
| etc. | |
| </code> | |
| <p><kbd>$this</kbd>, however, only works directly within your controllers, your models, or your views. | |
| If you would like to use Code Igniter's classes from within your own custom classes you can do so as follows:</p> | |
| <p>First, assign the Code Igniter object to a variable:</p> | |
| <code>$obj =& get_instance();</code> | |
| <p>Once you've assigned the object to a variable, you'll use that variable <em>instead</em> of <kbd>$this</kbd>:</p> | |
| <code> | |
| $obj =& get_instance();<br /><br /> | |
| $obj->load->helper('url');<br /> | |
| $obj->load->library('session');<br /> | |
| $obj->config->item('base_url');<br /> | |
| etc. | |
| </code> | |
| <p class="important"><strong>Note:</strong> You'll notice that the above get_instance() function is being passed by reference: | |
| <br /><br /> | |
| <var>$obj =& get_instance();</var> | |
| <br /><br /> | |
| <kbd>This is very important.</kbd> Assigning by reference allows you to use the original Code Igniter object rather than creating a copy of it.</p> | |
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