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Creating Core System Classes

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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.

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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. -

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Note: Messing with a core system class has a lot of implications, so make sure you -know what you are doing before attempting it.

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System Class List

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The following is a list of the core system files that are invoked every time CodeIgniter runs:

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Benchmark
Config
Controller
Exceptions
Hooks
Input
Language
Loader
Log
Output
Router
URI
Utf8

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Replacing Core Classes

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To use one of your own system classes instead of a default one simply place your version inside your local application/core directory:

- -application/core/some-class.php - -

If this directory does not exist you can create it.

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Any file named identically to one from the list above will be used instead of the one normally used.

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Please note that your class must use CI as a prefix. For example, if your file is named Input.php the class will be named:

- -


-class CI_Input {


-
-}
-

- - - -

Extending Core Class

- -

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:

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The class declaration must extend the parent class.
Your new class name and filename must be prefixed with MY_ (this item is configurable. See below.).

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For example, to extend the native Input class you'll create a file named application/core/MY_Input.php, and declare your class with:

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-class MY_Input extends CI_Input {


-
-}

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Note: If you need to use a constructor in your class make sure you extend the parent constructor:

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-class MY_Input extends CI_Input {

-

-    function __construct()

-    {

-        parent::__construct();

-    }

-}

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Tip: 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.

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If you are extending the Controller core class, then be sure to extend your new class in your application controller's constructors.

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class Welcome extends MY_Controller {

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-    function __construct()

-    {

-        parent::__construct();

-    }

-

-    function index()

-    {

-        $this->load->view('welcome_message');

-    }

-}

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Setting Your Own Prefix

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To set your own sub-class prefix, open your application/config/config.php file and look for this item:

- -$config['subclass_prefix'] = 'MY_'; - -

Please note that all native CodeIgniter libraries are prefixed with CI_ so DO NOT use that as your prefix.

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CodeIgniter User Guide Version 2.0.3

Creating Core System Classes

System Class List

Replacing Core Classes

Extending Core Class

Setting Your Own Prefix