change post upon save

[yjeanrenaud]

Hi,

i would like to change something in messages posted.
therefore I would have written a plugin on postdats_presave hook

PHP Code:

$checkcontent = $vbulletin->GPC['message'];
   if (strpos($checkcontent, "foo"))
   {  
    $newcontent=str_replace("foo", "bar",$checkcontent);
    $vbulletin->GPC['message'] = $newcontent;
   } 


is this how the plugin systems work?