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admin9fc347d2006-09-21 00:00:28 +0000[diff] [blame]36<td><h1>Code Igniter User Guide Version 1.4.1</h1></td>
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]37<td id="breadcrumb_right"><a href="../toc.html">Full Table of Contents</a></td>
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48<a href="http://www.codeigniter.com/">Code Igniter Home</a> &nbsp;&#8250;&nbsp;
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50Creating Libraries
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62
63<h1>Creating Libraries</h1>
64
65<p>When we use the term "Libraries" we are normally referring to the classes that are located in the <kbd>libraries</kbd>
66directory 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
67your <dfn>application</dfn> directory in order to maintain separation between your local resources and the global framework resources.</p>
68
69<h2>Storage</h2>
70
71<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>
72
73<ul>
74<li>application/<dfn>init</dfn></li>
75<li>application/<dfn>libraries</dfn></li>
76</ul>
77
78
79<h2>Anatomy of a Library</h2>
80
81<p>A class library consists of two components:</p>
82
83<ol>
84<li>An <kbd>init</kbd> file.</li>
85<li>A <kbd>class</kbd> file.</li>
86</ol>
87
88<h2>The Init File</h2>
89
90<p>An <kbd>init</kbd> file a small initialization file corresponding to each of your classes. The purpose of this file is to
91instantiate a particular class. Each init file must be named identically to your class file name, adding the "init_" prefix. For example, if your
92class is named <dfn>myclass.php</dfn> your init file will be named:</p>
93
94<code>init_myclass.php</code>
95
96<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>
97
98
99<code>&lt;?php if (!defined('BASEPATH')) exit('No direct script access allowed');<br />
100<br />
101if ( ! class_exists('<kbd>Myclass</kbd>'))<br />
102{<br />
103&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;require_once(APPPATH.'libraries/<kbd>Myclass</kbd>'.EXT);<br />
104}<br />
105<br />
106$obj =& get_instance();<br />
107$obj-><kbd>myclass</kbd> = new <kbd>Myclass();</kbd><br />
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]108<br />
109?&gt;</code>
110
111<h2>The Class File</h2>
112
113<p>Your class file itself will be placed inside your <dfn>libraries</dfn> directory:</p>
114
115<code>application/libraries/<dfn>myclass.php</dfn></code>
116
117<p>The class will have this basic prototype:</p>
118
119<code>&lt;?php if (!defined('BASEPATH')) exit('No direct script access allowed');<br />
120<br />
121class Myclass {<br />
122<br />
123}<br />
124?&gt;</code>
125
126
127<h2>Naming Conventions</h2>
128
129<ul>
130<li>All file names must be in lowercase: myclass.php and init_myclass.php</li>
131<li>Class names must be capitalize: class Myclass</li>
132</ul>
133
134
135<h2>Using Your Class</h2>
136
137<p>From within any of your <a href="controllers.html">Controller</a> classes you can initialize your class using the standard:</p>
138
139<code>$this->load->library('<kbd>myclass</kbd>');</code>
140
141<p>Once loaded you can access your class using:</p>
142
143<code>$this-><kbd>myclass</kbd>->function();</code>
144
145<p>Note: In your init file you can define the object variable name.</p>
146
147
148<h2>Passing Parameters Your Class</h2>
149
150<p>In the library loading function you can pass data via the second parameter and it will be available to your initialization file:</p>
151
152<code>
153$params = array('type' => 'large', 'color' => 'red');<br />
154<br />
155$this->load->library('myclass', <kbd>$params</kbd>);</code>
156
157<p>Parameters will be accessible using a variable called <kbd>$params</kbd>. By default this variable is set to FALSE.</p>
158
159
160<h2>Utilizing Code Igniter Resources within Your Library</h2>
161
162
163<p>To access Code Igniter's native resources within your library use the <kbd>get_instance()</kbd> function.
164This function returns the Code Igniter super object.</p>
165
166<p>Normally, to call any of the available Code Igniter functions requires you to use the <kbd>$this</kbd> construct:</p>
167
168<code>
169<strong>$this</strong>->load->helper('url');<br />
170<strong>$this</strong>->load->library('session');<br />
171<strong>$this</strong>->config->item('base_url');<br />
172etc.
173</code>
174
175<p><kbd>$this</kbd>, however, only works directly within your controllers, your models, or your views.
176If you would like to use Code Igniter's classes from within your own custom classes you can do so as follows:</p>
177
178
179<p>First, assign the Code Igniter object to a variable:</p>
180
181<code>$obj =& get_instance();</code>
182
183<p>Once you've assigned the object to a variable, you'll use that variable <em>instead</em> of <kbd>$this</kbd>:</p>
184
185<code>
186$obj =& get_instance();<br /><br />
187$obj->load->helper('url');<br />
188$obj->load->library('session');<br />
189$obj->config->item('base_url');<br />
190etc.
191</code>
192
193<p class="important"><strong>Note:</strong> You'll notice that the above get_instance() function is being passed by reference:
194<br /><br />
195<var>$obj =& get_instance();</var>
196<br /><br />
197<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>
198
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admina634e562006-08-25 22:19:55 +0000[diff] [blame]211Previous Topic:&nbsp;&nbsp;<a href="libraries.html">Using Code Igniter Libraries</a>
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admina634e562006-08-25 22:19:55 +0000[diff] [blame]215Next Topic:&nbsp;&nbsp;<a href="core_classes.html">Creating Core System Classes</a>
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]216<p>
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