bzr branch
http://gegoxaren.bato24.eu/bzr/lenasys/trunk
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20.1.1
by galaxyAbstractor
* Added an simple admin panel to the codeviewer-cmssy stuff |
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<title>Creating Libraries : CodeIgniter User Guide</title> |
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<table cellpadding="0" cellspacing="0" border="0" style="width:100%"> |
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<tr> |
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<td><h1>CodeIgniter User Guide Version 2.1.3</h1></td> |
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<td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td> |
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<a href="http://codeigniter.com/">CodeIgniter Home</a> › |
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<a href="../index.html">User Guide Home</a> › |
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Creating Libraries |
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<td id="searchbox"><form method="get" action="http://www.google.com/search"><input type="hidden" name="as_sitesearch" id="as_sitesearch" value="codeigniter.com/user_guide/" />Search User Guide <input type="text" class="input" style="width:200px;" name="q" id="q" size="31" maxlength="255" value="" /> <input type="submit" class="submit" name="sa" value="Go" /></form></td> |
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<!-- START CONTENT -->
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<div id="content"> |
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<h1>Creating Libraries</h1> |
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<p>When we use the term "Libraries" we are normally referring to the classes that are located in the <kbd>libraries</kbd> |
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directory and described in the Class Reference of this user guide. In this case, however, we will instead describe how you can create |
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your own libraries within your <dfn>application/libraries</dfn> directory in order to maintain separation between your local resources |
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and the global framework resources.</p> |
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<p>As an added bonus, CodeIgniter permits your libraries to <kbd>extend</kbd> native classes if you simply need to add some functionality |
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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> |
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<p>In summary:</p> |
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<ul> |
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<li>You can create entirely new libraries.</li> |
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<li>You can extend native libraries.</li> |
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<li>You can replace native libraries.</li> |
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</ul> |
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<p>The page below explains these three concepts in detail.</p> |
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<p class="important"><strong>Note:</strong> The Database classes can not be extended or replaced with your own classes. All other classes are able to be replaced/extended.</p> |
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<h2>Storage</h2> |
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<p>Your library classes should be placed within your <dfn>application/libraries</dfn> folder, as this is where CodeIgniter will look for them when |
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they are initialized.</p> |
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<h2>Naming Conventions</h2> |
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<ul> |
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<li>File names must be capitalized. For example: <dfn>Myclass.php</dfn></li> |
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<li>Class declarations must be capitalized. For example: <kbd>class Myclass</kbd></li> |
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<li>Class names and file names must match.</li> |
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</ul> |
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<h2>The Class File</h2> |
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<p>Classes should have this basic prototype (Note: We are using the name <kbd>Someclass</kbd> purely as an example):</p> |
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<code><?php if ( ! defined('BASEPATH')) exit('No direct script access allowed'); |
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<br /><br /> |
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class Someclass {<br />
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<br /> |
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public function some_function()<br /> |
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{<br /> |
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}<br /> |
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}<br /><br /> |
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/* End of file Someclass.php */</code> |
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<h2>Using Your Class</h2> |
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<p>From within any of your <a href="controllers.html">Controller</a> functions you can initialize your class using the standard:</p> |
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<code>$this->load->library('<kbd>someclass</kbd>');</code> |
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<p>Where <em>someclass</em> is the file name, without the ".php" file extension. You can submit the file name capitalized or lower case. |
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CodeIgniter doesn't care.</p> |
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<p>Once loaded you can access your class using the <kbd>lower case</kbd> version:</p> |
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<code>$this-><kbd>someclass</kbd>->some_function(); // Object instances will always be lower case |
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</code> |
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<h2>Passing Parameters When Initializing Your Class</h2> |
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<p>In the library loading function you can dynamically pass data as an array via the second parameter and it will be passed to your class |
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constructor:</p> |
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<code> |
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$params = array('type' => 'large', 'color' => 'red');<br />
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<br /> |
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$this->load->library('Someclass', <kbd>$params</kbd>);</code>
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<p>If you use this feature you must set up your class constructor to expect data:</p> |
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<code><?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');<br /> |
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<br /> |
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class Someclass {<br />
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<br /> |
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public function __construct($params)<br /> |
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{<br /> |
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// Do something with $params<br /> |
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}<br /> |
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}<br /><br /> |
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?></code> |
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<p class="important">You can also pass parameters stored in a config file. Simply create a config file named identically to the class <kbd>file name</kbd> |
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and store it in your <dfn>application/config/</dfn> folder. Note that if you dynamically pass parameters as described above, |
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the config file option will not be available.</p> |
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<h2>Utilizing CodeIgniter Resources within Your Library</h2> |
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<p>To access CodeIgniter's native resources within your library use the <kbd>get_instance()</kbd> function. |
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This function returns the CodeIgniter super object.</p> |
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<p>Normally from within your controller functions you will call any of the available CodeIgniter functions using the <kbd>$this</kbd> construct:</p> |
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<code> |
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<strong>$this</strong>->load->helper('url');<br /> |
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<strong>$this</strong>->load->library('session');<br /> |
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<strong>$this</strong>->config->item('base_url');<br /> |
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etc. |
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</code> |
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<p><kbd>$this</kbd>, however, only works directly within your controllers, your models, or your views. |
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If you would like to use CodeIgniter's classes from within your own custom classes you can do so as follows:</p> |
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<p>First, assign the CodeIgniter object to a variable:</p> |
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<code>$CI =& get_instance();</code> |
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<p>Once you've assigned the object to a variable, you'll use that variable <em>instead</em> of <kbd>$this</kbd>:</p> |
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<code> |
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$CI =& get_instance();<br /> |
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<br /> |
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$CI->load->helper('url');<br />
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$CI->load->library('session');<br />
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$CI->config->item('base_url');<br />
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etc. |
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</code> |
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<p class="important"><strong>Note:</strong> You'll notice that the above get_instance() function is being passed by reference: |
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<br /><br /> |
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<var>$CI =& get_instance();</var> |
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<br /> |
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<br /> |
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<kbd>This is very important.</kbd> Assigning by reference allows you to use the original CodeIgniter object rather than creating a copy of it.</p> |
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<h2>Replacing Native Libraries with Your Versions</h2> |
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<p>Simply by naming your class files identically to a native library will cause CodeIgniter to use it instead of the native one. To use this |
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feature you must name the file and the class declaration exactly the same as the native library. For example, to replace the native <kbd>Email</kbd> library |
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you'll create a file named <dfn>application/libraries/Email.php</dfn>, and declare your class with:</p> |
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<code> |
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class CI_Email {<br /><br />
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}</code> |
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<p>Note that most native classes are prefixed with <kbd>CI_</kbd>.</p> |
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<p>To load your library you'll see the standard loading function:</p> |
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<code>$this->load->library('<kbd>email</kbd>');</code> |
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<p class="important"><strong>Note:</strong> At this time the Database classes can not be replaced with your own versions.</p> |
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<h2>Extending Native Libraries</h2> |
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<p>If all you need to do is add some functionality to an existing library - perhaps add a function or two - then |
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it's overkill to replace the entire library with your version. In this case it's better to simply extend the class. |
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Extending a class is nearly identical to replacing a class with a couple exceptions:</p> |
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<ul> |
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<li>The class declaration must extend the parent class.</li> |
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<li>Your new class name and filename must be prefixed with <kbd>MY_</kbd> (this item is configurable. See below.).</li> |
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</ul> |
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<p>For example, to extend the native <kbd>Email</kbd> class you'll create a file named <dfn>application/libraries/</dfn><kbd>MY_Email.php</kbd>, and declare your class with:</p> |
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<code> |
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class MY_Email extends CI_Email {<br /><br />
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}</code> |
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<p>Note: If you need to use a constructor in your class make sure you extend the parent constructor:</p> |
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<code> |
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class MY_Email extends CI_Email {<br />
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<br /> |
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public function __construct()<br /> |
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{<br /> |
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parent::__construct();<br /> |
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}<br /> |
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}</code> |
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<h3>Loading Your Sub-class</h3> |
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<p>To load your sub-class you'll use the standard syntax normally used. DO NOT include your prefix. For example, |
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to load the example above, which extends the Email class, you will use:</p> |
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<code>$this->load->library('<kbd>email</kbd>');</code> |
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<p>Once loaded you will use the class variable as you normally would for the class you are extending. In the case of |
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the email class all calls will use:</p> |
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<code>$this-><kbd>email</kbd>->some_function();</code> |
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<h3>Setting Your Own Prefix</h3> |
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<p>To set your own sub-class prefix, open your <dfn>application/config/config.php</dfn> file and look for this item:</p> |
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<code>$config['subclass_prefix'] = 'MY_';</code> |
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<p>Please note that all native CodeIgniter libraries are prefixed with <kbd>CI_</kbd> so DO NOT use that as your prefix.</p> |
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</div> |
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<!-- END CONTENT -->
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<div id="footer"> |
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<p> |
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Previous Topic: <a href="libraries.html">Using CodeIgniter Libraries</a> |
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·
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<a href="#top">Top of Page</a> · |
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<a href="../index.html">User Guide Home</a> · |
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Next Topic: <a href="drivers.html">Using CodeIgniter Drivers</a> |
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</p> |
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<p><a href="http://codeigniter.com">CodeIgniter</a> · Copyright © 2006 - 2012 · <a href="http://ellislab.com/">EllisLab, Inc.</a></p> |
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