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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 |
| 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. |
| 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>$this</kbd> construct:</p> |
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| <strong>$this</strong>->load->helper('url');<br /> |
| <strong>$this</strong>->load->library('session');<br /> |
| <strong>$this</strong>->config->item('base_url');<br /> |
| etc. |
| </code> |
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| <p><kbd>$this</kbd>, however, only works within your controllers, your models, or your views. |
| If you would like to use CodeIgniter's classes from within your own custom classes you can do so as follows:</p> |
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| <p>First, assign the CodeIgniter object to a variable:</p> |
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| <code>$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> |
| $CI =& get_instance();<br /><br /> |
| $CI->load->helper('url');<br /> |
| $CI->load->library('session');<br /> |
| $CI->config->item('base_url');<br /> |
| etc. |
| </code> |
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| <p class="important"><strong>Note:</strong> You'll notice that the above get_instance() function is being passed by reference: |
| <br /><br /> |
| <var>$CI =& get_instance();</var> |
| <br /><br /> |
| 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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