Файл: CodeIgniter-3.0.3/user_guide/general/core_classes.html
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<div class="section" id="creating-core-system-classes">
<h1>Creating Core System Classes<a class="headerlink" href="#creating-core-system-classes" title="Permalink to this headline">¶</a></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>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">Messing with a core system class has a lot of implications, so
make sure you know what you are doing before attempting it.</p>
</div>
<div class="section" id="system-class-list">
<h2>System Class List<a class="headerlink" href="#system-class-list" title="Permalink to this headline">¶</a></h2>
<p>The following is a list of the core system files that are invoked every
time CodeIgniter runs:</p>
<ul class="simple">
<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>Security</li>
<li>URI</li>
<li>Utf8</li>
</ul>
</div>
<div class="section" id="replacing-core-classes">
<h2>Replacing Core Classes<a class="headerlink" href="#replacing-core-classes" title="Permalink to this headline">¶</a></h2>
<p>To use one of your own system classes instead of a default one simply
place your version inside your local <em>application/core/</em> directory:</p>
<div class="highlight-ci"><div class="highlight"><pre><span class="nx">application</span><span class="o">/</span><span class="nx">core</span><span class="o">/</span><span class="nx">some_class</span><span class="o">.</span><span class="nx">php</span>
</pre></div>
</div>
<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 CI as a prefix. For example, if
your file is named Input.php the class will be named:</p>
<div class="highlight-ci"><div class="highlight"><pre><span class="k">class</span> <span class="nc">CI_Input</span> <span class="p">{</span>
<span class="p">}</span>
</pre></div>
</div>
</div>
<div class="section" id="extending-core-class">
<h2>Extending Core Class<a class="headerlink" href="#extending-core-class" title="Permalink to this headline">¶</a></h2>
<p>If all you need to do is add some functionality to an existing library -
perhaps add a method 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 class="simple">
<li>The class declaration must extend the parent class.</li>
<li>Your new class name and filename must be prefixed with MY_ (this
item is configurable. See below.).</li>
</ul>
<p>For example, to extend the native Input class you’ll create a file named
application/core/MY_Input.php, and declare your class with:</p>
<div class="highlight-ci"><div class="highlight"><pre><span class="k">class</span> <span class="nc">MY_Input</span> <span class="k">extends</span> <span class="nx">CI_Input</span> <span class="p">{</span>
<span class="p">}</span>
</pre></div>
</div>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p>If you need to use a constructor in your class make sure you
extend the parent constructor:</p>
<div class="last highlight-ci"><div class="highlight"><pre><span class="k">class</span> <span class="nc">MY_Input</span> <span class="k">extends</span> <span class="nx">CI_Input</span> <span class="p">{</span>
<span class="k">public</span> <span class="k">function</span> <span class="nf">__construct</span><span class="p">()</span>
<span class="p">{</span>
<span class="k">parent</span><span class="o">::</span><span class="na">__construct</span><span class="p">();</span>
<span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
</div>
<p><strong>Tip:</strong> Any functions in your class that are named identically to the
methods 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>
<div class="highlight-ci"><div class="highlight"><pre><span class="k">class</span> <span class="nc">Welcome</span> <span class="k">extends</span> <span class="nx">MY_Controller</span> <span class="p">{</span>
<span class="k">public</span> <span class="k">function</span> <span class="nf">__construct</span><span class="p">()</span>
<span class="p">{</span>
<span class="k">parent</span><span class="o">::</span><span class="na">__construct</span><span class="p">();</span>
<span class="p">}</span>
<span class="k">public</span> <span class="k">function</span> <span class="nf">index</span><span class="p">()</span>
<span class="p">{</span>
<span class="nv">$this</span><span class="o">-></span><span class="na">load</span><span class="o">-></span><span class="na">view</span><span class="p">(</span><span class="s1">'welcome_message'</span><span class="p">);</span>
<span class="p">}</span>
<span class="p">}</span>
</pre></div>
</div>
<div class="section" id="setting-your-own-prefix">
<h3>Setting Your Own Prefix<a class="headerlink" href="#setting-your-own-prefix" title="Permalink to this headline">¶</a></h3>
<p>To set your own sub-class prefix, open your
<em>application/config/config.php</em> file and look for this item:</p>
<div class="highlight-ci"><div class="highlight"><pre><span class="nv">$config</span><span class="p">[</span><span class="s1">'subclass_prefix'</span><span class="p">]</span> <span class="o">=</span> <span class="s1">'MY_'</span><span class="p">;</span>
</pre></div>
</div>
<p>Please note that all native CodeIgniter libraries are prefixed
with CI_ so DO NOT use that as your prefix.</p>
</div>
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