blob: a81682399c4dda26b0cf704474f09c6235392c61 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Creating Core System Classes : CodeIgniter User Guide</title>
<style type='text/css' media='all'>@import url('../userguide.css');</style>
<link rel='stylesheet' type='text/css' media='all' href='../userguide.css' />
<script type="text/javascript" src="../nav/nav.js"></script>
<script type="text/javascript" src="../nav/prototype.lite.js"></script>
<script type="text/javascript" src="../nav/moo.fx.js"></script>
<script type="text/javascript" src="../nav/user_guide_menu.js"></script>
<meta http-equiv='expires' content='-1' />
<meta http-equiv= 'pragma' content='no-cache' />
<meta name='robots' content='all' />
<meta name='author' content='ExpressionEngine Dev Team' />
<meta name='description' content='CodeIgniter User Guide' />
</head>
<body>
<!-- START NAVIGATION -->
<div id="nav"><div id="nav_inner"><script type="text/javascript">create_menu('../');</script></div></div>
<div id="nav2"><a name="top"></a><a href="javascript:void(0);" onclick="myHeight.toggle();"><img src="../images/nav_toggle_darker.jpg" width="154" height="43" border="0" title="Toggle Table of Contents" alt="Toggle Table of Contents" /></a></div>
<div id="masthead">
<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
<tr>
<td><h1>CodeIgniter User Guide Version 1.7</h1></td>
<td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td>
</tr>
</table>
</div>
<!-- END NAVIGATION -->
<!-- START BREADCRUMB -->
<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
<tr>
<td id="breadcrumb">
<a href="http://codeigniter.com/">CodeIgniter Home</a> ›
<a href="../index.html">User Guide Home</a> ›
Creating Core System Classes
</td>
<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>
</tr>
</table>
<!-- END BREADCRUMB -->
<br clear="all" />
<!-- START CONTENT -->
<div id="content">
<h1>Creating Core System Classes</h1>
<p>Every time CodeIgniter runs there are several base classes that are initialized automatically as part of the core framework.
It is possible, however, to swap any of the core system classes with your own versions or even extend the core versions.</p>
<p><strong>Most users will never have any need to do this,
but the option to replace or extend them does exist for those who would like to significantly alter the CodeIgniter core.</strong>
</p>
<p class="important"><strong>Note:</strong> Messing with a core system class has a lot of implications, so make sure you
know what you are doing before attempting it.</p>
<h2>System Class List</h2>
<p>The following is a list of the core system files that are invoked every time CodeIgniter runs:</p>
<ul>
<li>Benchmark</li>
<li>Config</li>
<li>Controller</li>
<li>Exceptions</li>
<li>Hooks</li>
<li>Input</li>
<li>Language</li>
<li>Loader</li>
<li>Log</li>
<li>Output</li>
<li>Router</li>
<li>URI</li>
</ul>
<h2>Replacing Core Classes</h2>
<p>To use one of your own system classes instead of a default one simply place your version inside your local <dfn>application/libraries</dfn> directory:</p>
<code>application/libraries/<dfn>some-class.php</dfn></code>
<p>If this directory does not exist you can create it.</p>
<p>Any file named identically to one from the list above will be used instead of the one normally used.</p>
<p>Please note that your class must use <kbd>CI</kbd> as a prefix. For example, if your file is named <kbd>Input.php</kbd> the class will be named:</p>
<code>
class CI_Input {<br /><br />
}
</code>
<h2>Extending Core Class</h2>
<p>If all you need to do is add some functionality to an existing library - perhaps add a function or two - then
it's overkill to replace the entire library with your version. In this case it's better to simply extend the class.
Extending a class is nearly identical to replacing a class with a couple exceptions:</p>
<ul>
<li>The class declaration must extend the parent class.</li>
<li>Your new class name and filename must be prefixed with <kbd>MY_</kbd> (this item is configurable. See below.).</li>
</ul>
<p>For example, to extend the native <kbd>Input</kbd> class you'll create a file named <dfn>application/libraries/</dfn><kbd>MY_Input.php</kbd>, and declare your class with:</p>
<code>
class MY_Input extends CI_Input {<br /><br />
}</code>
<p>Note: If you need to use a constructor in your class make sure you extend the parent constructor:</p>
<code>
class MY_Input extends CI_Input {<br />
<br />
function My_Input()<br />
{<br />
parent::CI_Input();<br />
}<br />
}</code>
<p class="important"><strong>Tip:</strong> Any functions in your class that are named identically to the functions in the parent class will be used instead of the native ones
(this is known as "method overriding").
This allows you to substantially alter the CodeIgniter core.</p>
<p>If you are extending the Controller core class, then be sure to extend your new class in your application controller's constructors.</p>
<code>class Welcome extends MY_Controller {<br />
<br />
function Welcome()<br />
{<br />
parent::MY_Controller();<br />
}<br />
<br />
function index()<br />
{<br />
$this->load->view('welcome_message');<br />
}<br />
}</code>
<h3>Setting Your Own Prefix</h3>
<p>To set your own sub-class prefix, open your <dfn>application/config/config.php</dfn> file and look for this item:</p>
<code>$config['subclass_prefix'] = 'MY_';</code>
<p>Please note that all native CodeIgniter libraries are prefixed with <kbd>CI_</kbd> so DO NOT use that as your prefix.</p>
</div>
<!-- END CONTENT -->
<div id="footer">
<p>
Previous Topic: <a href="creating_libraries.html">Creating Your Own Libraries</a>
·
<a href="#top">Top of Page</a> ·
<a href="../index.html">User Guide Home</a> ·
Next Topic: <a href="hooks.html">Hooks - Extending the Core</a>
</p>
<p><a href="http://codeigniter.com">CodeIgniter</a> · Copyright © 2006-2008 · <a href="http://ellislab.com/">Ellislab, Inc.</a></p>
</div>
</body>
</html>
|
