yii get base url

Get Base Url YII Framework

echo Yii::app()->request->baseUrl."<br/>" ;
print_r(Yii::app()->request->baseUrl);
echo "<br/>";
var_dump(Yii::app()->getBaseUrl(true));
echo "<br/>";
echo Yii::app()->request->getBaseUrl(true);

You're right, you can't use the Yii::app() methods inside the config's return array, but you can use Yii::getPathOfAlias() outside. Something like this might work:

$webroot = Yii::getPathOfAlias('webroot');
return array(
    ...
    'params'=>array(
        'paths' => array(
            'imageTemp'=> $webroot.'/files/temp-',
            'image'=> $webroot.'/files/',
            ...
        ),
    ),
);

return array(
    ...
    'urls'=>array(
        'paths' => array(
            'imageTemp'=> '/files/temp-',
            'image'=> '/files/',
            ...
        ),
    ),
);