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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;
49<a href="../index.html">User Guide Home</a> &nbsp;&#8250;&nbsp;
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 />
108$obj->ci_is_loaded[] = '<kbd>myclass</kbd>';<br />
109<br />
110?&gt;</code>
111
112<h2>The Class File</h2>
113
114<p>Your class file itself will be placed inside your <dfn>libraries</dfn> directory:</p>
115
116<code>application/libraries/<dfn>myclass.php</dfn></code>
117
118<p>The class will have this basic prototype:</p>
119
120<code>&lt;?php if (!defined('BASEPATH')) exit('No direct script access allowed');<br />
121<br />
122class Myclass {<br />
123<br />
124}<br />
125?&gt;</code>
126
127
128<h2>Naming Conventions</h2>
129
130<ul>
131<li>All file names must be in lowercase: myclass.php and init_myclass.php</li>
132<li>Class names must be capitalize: class Myclass</li>
133</ul>
134
135
136<h2>Using Your Class</h2>
137
138<p>From within any of your <a href="controllers.html">Controller</a> classes you can initialize your class using the standard:</p>
139
140<code>$this->load->library('<kbd>myclass</kbd>');</code>
141
142<p>Once loaded you can access your class using:</p>
143
144<code>$this-><kbd>myclass</kbd>->function();</code>
145
146<p>Note: In your init file you can define the object variable name.</p>
147
148
149<h2>Passing Parameters Your Class</h2>
150
151<p>In the library loading function you can pass data via the second parameter and it will be available to your initialization file:</p>
152
153<code>
154$params = array('type' => 'large', 'color' => 'red');<br />
155<br />
156$this->load->library('myclass', <kbd>$params</kbd>);</code>
157
158<p>Parameters will be accessible using a variable called <kbd>$params</kbd>. By default this variable is set to FALSE.</p>
159
160
161<h2>Utilizing Code Igniter Resources within Your Library</h2>
162
163
164<p>To access Code Igniter's native resources within your library use the <kbd>get_instance()</kbd> function.
165This function returns the Code Igniter super object.</p>
166
167<p>Normally, to call any of the available Code Igniter functions requires you to use the <kbd>$this</kbd> construct:</p>
168
169<code>
170<strong>$this</strong>->load->helper('url');<br />
171<strong>$this</strong>->load->library('session');<br />
172<strong>$this</strong>->config->item('base_url');<br />
173etc.
174</code>
175
176<p><kbd>$this</kbd>, however, only works directly within your controllers, your models, or your views.
177If you would like to use Code Igniter's classes from within your own custom classes you can do so as follows:</p>
178
179
180<p>First, assign the Code Igniter object to a variable:</p>
181
182<code>$obj =& get_instance();</code>
183
184<p>Once you've assigned the object to a variable, you'll use that variable <em>instead</em> of <kbd>$this</kbd>:</p>
185
186<code>
187$obj =& get_instance();<br /><br />
188$obj->load->helper('url');<br />
189$obj->load->library('session');<br />
190$obj->config->item('base_url');<br />
191etc.
192</code>
193
194<p class="important"><strong>Note:</strong> You'll notice that the above get_instance() function is being passed by reference:
195<br /><br />
196<var>$obj =& get_instance();</var>
197<br /><br />
198<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>
199
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