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Derek Allardd2df9bc2007-04-15 17:41:17 +0000[diff] [blame]5<title>CodeIgniter User Guide</title>
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Derek Allardd2df9bc2007-04-15 17:41:17 +0000[diff] [blame]36<td><h1>CodeIgniter User Guide Version 1.5.3</h1></td>
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50Creating Ancillary Classes
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63<h1>Creating Ancillary Classes</h1>
64
admine334c472006-10-21 19:44:22 +0000[diff] [blame]65<p>In some cases you may want to develop classes that exist apart from your controllers but have the ability to
Derek Allardd2df9bc2007-04-15 17:41:17 +0000[diff] [blame]66utilize all of CodeIgniter's resources. This is easily possible as you'll see.</p>
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]67
68<h2>get_instance()</h2>
69
70
Derek Allardd2df9bc2007-04-15 17:41:17 +0000[diff] [blame]71<p><strong>Any class that you instantiate within your controller functions can access CodeIgniter's native resources</strong> simply by using the <kbd>get_instance()</kbd> function.
72This function returns the main CodeIgniter object.</p>
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]73
Derek Allardd2df9bc2007-04-15 17:41:17 +0000[diff] [blame]74<p>Normally, to call any of the available CodeIgniter functions requires you to use the <kbd>$this</kbd> construct:</p>
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]75
76<code>
77<strong>$this</strong>->load->helper('url');<br />
78<strong>$this</strong>->load->library('session');<br />
79<strong>$this</strong>->config->item('base_url');<br />
80etc.
81</code>
82
admine334c472006-10-21 19:44:22 +0000[diff] [blame]83<p><kbd>$this</kbd>, however, only works within your controllers, your models, or your views.
Derek Allardd2df9bc2007-04-15 17:41:17 +0000[diff] [blame]84If you would like to use CodeIgniter's classes from within your own custom classes you can do so as follows:</p>
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]85
86
Derek Allardd2df9bc2007-04-15 17:41:17 +0000[diff] [blame]87<p>First, assign the CodeIgniter object to a variable:</p>
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]88
admin88a8ad12006-10-07 03:16:32 +0000[diff] [blame]89<code>$CI =& get_instance();</code>
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]90
91<p>Once you've assigned the object to a variable, you'll use that variable <em>instead</em> of <kbd>$this</kbd>:</p>
92
93<code>
admin88a8ad12006-10-07 03:16:32 +0000[diff] [blame]94$CI =& get_instance();<br /><br />
95$CI->load->helper('url');<br />
96$CI->load->library('session');<br />
97$CI->config->item('base_url');<br />
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]98etc.
99</code>
100
101<p class="important"><strong>Note:</strong> You'll notice that the above get_instance() function is being passed by reference:
102<br /><br />
admin88a8ad12006-10-07 03:16:32 +0000[diff] [blame]103<var>$CI =& get_instance();</var>
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]104<br /><br />
Derek Allardd2df9bc2007-04-15 17:41:17 +0000[diff] [blame]105This is very important. Assigning by reference allows you to use the original CodeIgniter object rather than creating a copy of it.</p>
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Derek Allardd2df9bc2007-04-15 17:41:17 +0000[diff] [blame]118<p><a href="http://www.codeigniter.com">CodeIgniter</a> &nbsp;&middot;&nbsp; Copyright &#169; 2007 &nbsp;&middot;&nbsp; <a href="http://ellislab.com/">Ellislab, Inc.</a></p>
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