117 lines
4.7 KiB
HTML
117 lines
4.7 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<title>Creating Ancillary Classes : CodeIgniter User Guide</title>
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<style type='text/css' media='all'>@import url('../userguide.css');</style>
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<link rel='stylesheet' type='text/css' media='all' href='../userguide.css' />
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<script type="text/javascript" src="../nav/nav.js"></script>
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<script type="text/javascript" src="../nav/prototype.lite.js"></script>
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<script type="text/javascript" src="../nav/moo.fx.js"></script>
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<script type="text/javascript" src="../nav/user_guide_menu.js"></script>
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<meta http-equiv='expires' content='-1' />
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<meta http-equiv= 'pragma' content='no-cache' />
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<meta name='robots' content='all' />
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<meta name='author' content='ExpressionEngine Dev Team' />
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<meta name='description' content='CodeIgniter User Guide' />
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</head>
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<body>
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<!-- START NAVIGATION -->
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<div id="nav"><div id="nav_inner"><script type="text/javascript">create_menu('../');</script></div></div>
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<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>
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<div id="masthead">
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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 2.1.4</h1></td>
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<td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td>
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</tr>
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</table>
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</div>
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<!-- END NAVIGATION -->
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<!-- START BREADCRUMB -->
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<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
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<tr>
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<td id="breadcrumb">
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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 Ancillary Classes
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</td>
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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="ellislab.com/codeigniter/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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</tr>
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</table>
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<!-- END BREADCRUMB -->
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<br clear="all" />
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<!-- START CONTENT -->
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<div id="content">
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<h1>Creating Ancillary Classes</h1>
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<p>In some cases you may want to develop classes that exist apart from your controllers but have the ability to
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utilize all of CodeIgniter's resources. This is easily possible as you'll see.</p>
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<h2>get_instance()</h2>
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<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.
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This function returns the main CodeIgniter object.</p>
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<p>Normally, to call any of the available CodeIgniter functions requires you to use 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>$this</kbd>, however, only works within your controllers, your models, or your views.
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If you would like to use CodeIgniter's classes from within your own custom classes you can do so as follows:</p>
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<p>First, assign the CodeIgniter object to a variable:</p>
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<code>$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 /><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 /><br />
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This 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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</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="creating_libraries.html">Creating Core 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="autoloader.html">Auto-loading Resources</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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</div>
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</body>
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</html>
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