How do I include or autoload external libraries in a TYPO3 Extbase Extension? + Dependecy Injection?

Question

I'm developing a TYPO3 4.6 Extension with Extbase 1.4 and im trying to include an external library. The library, in my case the facebook PHP SDK, is under $_EXTKEY/Resources/PHP/facebook-php-sdk/facebook.php. I would like the library to autoload and automatically inject (Dependecy Injection) where I need it.

Some comments I found online suggest that one should include libraries with require_once():

http://forge.typo3.org/issues/33142

1. if it's just a tiny helper library, it's intended to be stored in {PackageRoot}/Resources/PHP/{libraryName} and just included via require. is this suspected by the problem however?
2. if the FLOW3 package mainly represents the foreing library at all, like it's the case in Imagine or Swift package, the library code is put below {PackageRoot}/Classes directly."

http://lists.typo3.org/pipermail/typo3-project-typo3v4mvc/2011-July/009946.html

"I would include the class (using require_once) from within a specific action to handle this. That way you have access over those functions and the class becomes your library."

I tried this and it works like this:

<?php
require_once( t3lib_extMgm::extPath('extkey') . 'Resources/PHP/facebook-php-sdk/facebook.php');

class Tx_WsLogin_Domain_Repository_FacebookUserRepository extends Tx_WsLogin_Domain_Repository_UserRepository {

protected $facebook;

public function __construct() {
    $this->setFacebook(new Facebook(array(
        'appId' =>'',
        'secret' => '')
    ));
    parent::__construct();
}

public function setFacebook(Facebook $facebook) {
    $this->facebook = $facebook;
}


public function sampleFunction() {
    $userId = $this->facebook->getUser();
}

}
?>

But how can I get it to autoload and automatically inject the library with the injectFacebook function?

edit:

Like @alex_schnitzler and @sorenmalling mentioned about autoloading:

@PeterTheOne Put all the files inside ext_autoload.php and then use DI or the object manager.

@PeterTheOne put the class definition into ext_autoload.php in your extension?

I tried it like this (file: ext_autoload.php):

<?php

$extPath = t3lib_extMgm::extPath('extKey');

return array(
    'facebook' => $extPath . 'Resources/PHP/facebook-php-sdk/facebook.php',
);

?>

It seems to find and include the right file. But when I try to user Dependency Injection (like peter answered) I get an error:

not a correct info array of constructor dependencies was passed!

InvalidArgumentException thrown in file /var/syscp/webs/web1/dev/typo3_src-4.5.15/typo3/sysext/extbase/Classes/Object/Container/Container.php in line 247.

I think this is because the constructor of the Facebook class has a required $config argument.

edit2:

I did what peter said in his answer and with the help of @alex_schnitzler and @sorenmalling, who pointed me to the ObjectManager, my FacebookService looks like this now:

class Tx_Extkey_Service_FacebookService implements t3lib_Singleton {

/**
* @var Tx_Extbase_Object_ObjectManagerInterface
*/
protected $objectManager;

/**
 * Facebook from @link https://github.com/facebook/facebook-php-sdk facebook-php-sdk
 *
 * @var Facebook
 */
protected $facebook;

/**
* @param Tx_Extbase_Object_ObjectManagerInterface $objectManager
*/
public function injectObjectManager(Tx_Extbase_Object_ObjectManagerInterface $objectManager) {
    $this->objectManager = $objectManager;
}

/**
 * 
 */
public function initializeObject() {
    $this->facebook = $this->objectManager->create(
        'Facebook',
        array(
            'appId' =>'input appId here',
            'secret' => 'input app secret here'
        )
    );
}

/**
 * @return Facebook
 */
public function getFacebook() {
    return $this->facebook;
}

}

For more help read: http://forge.typo3.org/projects/typo3v4-mvc/wiki/Dependency_Injection_(DI) the parts about initializeObject() and Creating Prototype Objects through the Object Manager

Answer 1

First create ext_autoload.php in extension root folder

and add your code,it contain single dimension array with key as class name(class name must be prefix with extension key) and value as path to file. make sure clear your site

<?php

    $extensionPath = \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::extPath('rent_system');
    return array(   
        'rent_system_TCPDF' => $extensionPath.'Resources/Private/PHP/tcpdf/tcpdf.php',  
    );
?>

In controller file

$pdf = $this->objectManager->create('rent_system_TCPDF');