Package =TWiki::AccessControlException 
extends Error
Exception used raise an access control violation.
 ClassMethod new ($mode,$user,$web,$topic,$reason) 
 
-  
$mode - mode of access (view, change etc)
  -  
$user - user object doing the accessing
  -  
$web - web being accessed
  -  
$topic - topic being accessed
  -  
$reason - string reason for failure
 
 
All the above fields are accessible from the object in a catch clause
in the usual way e.g. 
$e->{web} and 
$e->{reason}
Generate a summary string