Package =TWiki::Access 
A singleton object of this class manages the access control database.
Construct a new singleton object to manage the permissions
database.
 ObjectMethod permissionsSet ($web) -> $boolean 
Are there any security restrictions for this Web
(ignoring settings on individual pages).
Return a string describing the reason why the last access control failure
occurred.
 ObjectMethod *checkAccessPermission ($action,$user,$text,$topic,$web) -> $boolean 
Check if user is allowed to access topic 
-  
$action  - 'VIEW', 'CHANGE', 'CREATE', etc.
  -  
$user    - User object
  -  
$text    - If undef or '': Read '$theWebName.$theTopicName' to check permissions
  -  
$topic   - Topic name to check, e.g. 'SomeTopic' *undef to check web perms only)
  -  
$web     - Web, e.g. 'Know'
 
 
If the check fails, the reason can be recoveered using getReason.