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| <td><h1>Code Igniter User Guide Version 1.5.0</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/libraries</dfn> directory in order to maintain separation between your local resources | |
| and the global framework resources.</p> | |
| <p>As an added bonus, Code Igniter permits your libraries to <kbd>extend</kbd> native classes if you simply need to add some functionality | |
| to an existing library. Or you can even replace native libraries just by placing identically named versions in your <dfn>application/libraries</dfn> folder. | |
| <p>In summary:</p> | |
| <ul> | |
| <li>You can create entirely new libraries.</li> | |
| <li>You can extend native libraries.</li> | |
| <li>You can replace native libraries.</li> | |
| </ul> | |
| <h2>Storage</h2> | |
| <p>Your library classes should be placed within your <dfn>application/libraries</dfn> folder, as this is where Code Igniter will look for them when | |
| they are initialized.</p> | |
| <h2>Naming Conventions</h2> | |
| <ul> | |
| <li>File names must be capitalized. For example: <dfn>Myclass.php</dfn></li> | |
| <li>Class declarations must be capitalized. For example: <kbd>class Myclass</kbd></li> | |
| <li>Class names and file names must match.</li> | |
| </ul> | |
| <h2>The Class File</h2> | |
| <p>Classes should have this basic prototype (Note: We are using the name <kbd>Myclass</kbd> purely as an example):</p> | |
| <code><?php if (!defined('BASEPATH')) exit('No direct script access allowed');<br /> | |
| <br /><br /> | |
| class Myclass {<br /> | |
| <br /> | |
| function some_function()<br /> | |
| {<br /> | |
| }<br /> | |
| }<br /><br /> | |
| ?></code> | |
| <h2>Using Your Class</h2> | |
| <p>From within any of your <a href="controllers.html">Controller</a> functions you can initialize your class using the standard:</p> | |
| <code>$this->load->library('<kbd>Mclass</kbd>');</code> | |
| <p>Where <em>Myclass</em> is the file name, without the ".php" file extension. You can submit the file name capitalized or lower case. | |
| Code Igniter doesn't care.</p> | |
| <p>Once loaded you can access your class using:</p> | |
| <code>$this-><kbd>myclass</kbd>->some_function(); // Object instances will always be lower case | |
| </code> | |
| <h2>Passing Parameters When Initializing Your Class</h2> | |
| <p>In the library loading function you can dynamically pass data via the second parameter and it will be passed to your class | |
| constructor:</p> | |
| <code> | |
| $params = array('type' => 'large', 'color' => 'red');<br /> | |
| <br /> | |
| $this->load->library('Myclass', <kbd>$params</kbd>);</code> | |
| <p>If you use this feature you must set up your class constructor to expect data:</p> | |
| <code><?php if (!defined('BASEPATH')) exit('No direct script access allowed');<br /> | |
| <br /> | |
| // Initialize the class<br /> | |
| $obj =& get_instance();<br /> | |
| $obj->init_class('Myclass'); | |
| <br /><br /> | |
| class Myclass {<br /> | |
| <br /> | |
| function Myclass($params)<br /> | |
| {<br /> | |
| // Do something with $params<br /> | |
| }<br /> | |
| }<br /><br /> | |
| ?></code> | |
| <p>You can also pass parameters stored in a config file. Simply create a config file named identically to the class filename.</p> | |
| <h2>Utilizing Code Igniter Resources within Your Library</h2> | |
| <p>To access Code Igniter's native resources within your library use the <kbd>get_instance()</kbd> function. | |
| This function returns the Code Igniter super object.</p> | |
| <p>Normally from within your controller functions you will call any of the available Code Igniter functions using the <kbd>$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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