+++
title = "Extensions"
linkTitle = "Engine Extensions"
[menu.main]
parent = "engine"
weight = 5
+++
Creating extensions couldn't be easier, and can really make Plates sing for your specific project. Start by creating a class that implements `\League\Plates\Extension\ExtensionInterface`. Next, register your template [functions]({{< relref "engine/functions.md" >}}) within a `register()` method.
## Simple extensions example
~~~ php
use League\Plates\Engine;
use League\Plates\Extension\ExtensionInterface;
class ChangeCase implements ExtensionInterface
{
public function register(Engine $engine)
{
$engine->registerFunction('uppercase', [$this, 'uppercaseString']);
$engine->registerFunction('lowercase', [$this, 'lowercaseString']);
}
public function uppercaseString($var)
{
return strtoupper($var);
}
public function lowercaseString($var)
{
return strtolower($var);
}
}
~~~
To use this extension in your template, simply call your new functions:
~~~ php
<p>Hello, <?=$this->e($this->uppercase($name))?></p>
~~~
They can also be used in a [batch]({{< relref "templates/functions.md#batch-function-calls" >}}) compatible function:
~~~ php
<h1>Hello <?=$this->e($name, 'uppercase')</h1>
~~~
## Single method extensions
Alternatively, you may choose to expose the entire extension object to the template using a single function. This can make your templates more legible and also reduce the chance of conflicts with other extensions.
~~~ php
use League\Plates\Engine;
use League\Plates\Extension\ExtensionInterface;
class ChangeCase implements ExtensionInterface
{
public function register(Engine $engine)
{
$engine->registerFunction('case', [$this, 'getObject']);
}
public function getObject()
{
return $this;
}
public function upper($var)
{
return strtoupper($var);
}
public function lower($var)
{
return strtolower($var);
}
}
~~~
To use this extension in your template, first call the primary function, then the secondary functions:
~~~ php
<p>Hello, <?=$this->e($this->case()->upper($name))?></p>
~~~
## Loading extensions
To enable an extension, load it into the [engine]({{< relref "engine/overview.md" >}}) object using the `loadExtension()` method.
~~~ php
$engine->loadExtension(new ChangeCase());
~~~
## Accessing the engine and template
It may be desirable to access the `engine` or `template` objects from within your extension. Plates makes both of these objects available to you. The engine is automatically passed to the `register()` method, and the template is assigned as a parameter on each function call.
~~~ php
use League\Plates\Engine;
use League\Plates\Extension\ExtensionInterface;
class MyExtension implements ExtensionInterface
{
protected $engine;
public $template; // must be public
public function register(Engine $engine)
{
$this->engine = $engine;
// Access template data:
$data = $this->template->data();
// Register functions
// ...
}
}
~~~