which is the best place to initialize the Yii::app()->language?
I don’t want to initialize in config/main.php because I am going to set that programmatically.
I thought to do that in components/controller.php but I am using a few modules which are not inherit the components/Controller class.
CController::init()
Check out the wiki: setting language in application.
So, I have to add language functionallity on "My Controller" to inherit all Controllers from this class. So if I have many "My Controllers" it could inherit the main "My Controller" (multi-level inheritance) right?
Yes.
And if you override init() method you need to call parent::init():
public function init() {
parent::init();
// your code here
}
there is by default "Controller" class in protected/components of which all other generated controllers are descendants. You can just put your init() code there.
Ha-ha, redguy… good old Cow & Chicken. 
Yes I know that. But I have 2-3 different Controllers in components folder. Now I make it to inherit the base components/Controller. I run initialize it into __construct(). Thanks
yep 
A bit late but another solution that is independent from the controller is to set the language in a handler for the ‘onBeginReuest’ application event. Here is the code for a behavior that does exactly that:
class SetLanguageBehavior extends CBehavior
{
/**
* @inheritDoc
*/
public function events()
{
return array(
'onBeginRequest' => 'beginRequestHandler',
);
}
/**
* Sets the language based on application configuration and browser settings.
*/
public function beginRequestHandler($event)
{
$app = $this->getOwner();
$lang = $app->getRequest()->getPreferredLanguage();
// ADD YOUR OWN LOGIC HERE, E.G. SETTING THE LANGUAGE FROM THE DB
if ($lang == $app->sourceLanguage)
$lang = null;
$app->setLanguage($lang);
}
}
Then just add the behavior to the application in the main config:
...
'behaviors' => array(
'setLanguageBehavior' => array(
'class' => 'SetLanguageBehavior',
),
),
...