__Note:__ in all the following documentation, =$user= refers to a

 __Note:__ in all the following documentation, =$cUID= refers to a

 Default is *false*

 The user can be identified by any of $cUID, $login or $wikiname. Any of

 these parameters may be undef, and they should be tested in order; cUID

 first, then login, then wikiname.

 ---++ ObjectMethod *getCanonicalUserID* <tt>($login,$dontcheck) -> cUID</tt>

 ---++ ObjectMethod *login2cUID* <tt>($login,$dontcheck) -> cUID</tt>

 characters, and must correspond 1:1 to the login name.

 characters, and must map 1:1 to the login name.

 (if dontcheck is true, return a cUID for a nonexistant user too - used for registration)

 (if $dontcheck is true, return a cUID for a nonexistant user too.

 This is used for registration)

 Subclasses *must* implement this method.

 Subclasses *must* implement this method.

 Note: This method was previously (in TWiki 4.2.0) known as getCanonicalUserID.

 The name was changed to avoid confusion with TWiki::Users::getCanonicalUserID,

 which has a more generic function. However to support older user mappers,

 getCanonicalUserID will still be called if login2cUID is not defined.

 ---++ ObjectMethod *addUser* <tt>($login,$wikiname,$password,$emails) -> cUID</tt>

 ---++ ObjectMethod *addUser* <tt>($login,$wikiname,$password,$emails) -> $cUID</tt>

 and vice-versa, via a *canonical user id* (cUID).

 and vice-versa.

 ---++ ObjectMethod *removeUser* <tt>($user) -> $boolean</tt>

 ---++ ObjectMethod *removeUser* <tt>($cUID) -> $boolean</tt>

 ---++ ObjectMethod *getWikiName* <tt>($cUID) -> wikiname</tt>

 ---++ ObjectMethod *getWikiName* <tt>($cUID) -> $wikiname</tt>

 ---++ ObjectMethod *eachUser* <tt>() -> listIteratorofcUIDs</tt>

 ---++ ObjectMethod *eachUser* <tt>() -> TWiki::ListIteratorofcUIDs</tt>

 Called from TWiki::Users. See the documentation of the corresponding

 Get an iterator over the list of all the registered users *not* including

 method in that module for details.

 groups.

 Called from TWiki::Users. See the documentation of the corresponding

 Return a iterator over the canonical user ids of users that are members

 method in that module for details.

 of this group. Should only be called on groups.

 Subclasses *must* implement this method.

 Note that groups may be defined recursively, so a group may contain other

 groups. This method should *only* return users i.e. all contained groups

 should be fully expanded.

 ---++ ObjectMethod *isGroup* <tt>($user) -> boolean</tt>

 Subclasses *must* implement this method.

 Called from TWiki::Users. See the documentation of the corresponding

 method in that module for details.

 ---++ ObjectMethod *isGroup* <tt>($name) -> boolean</tt>

 Subclasses *must* implement this method.

 Establish if a user refers to a group or not. If $name is not

 a group name it will probably be a canonical user id, though that

 should not be assumed.

 ---++ ObjectMethod *eachGroup* <tt>() -> ListIteratorofgroupnames</tt>

 Subclasses *must* implement this method.

 Called from TWiki::Users. See the documentation of the corresponding

 method in that module for details.

 Subclasses *must* implement this method.

 ---++ ObjectMethod *eachGroup* <tt>() -> TWiki::ListIteratorofgroupnames</tt>

 Get an iterator over the list of all the groups.

 ---++ ObjectMethod *eachMembership* <tt>($cUID) -> ListIteratorofgroupsthisuserisin</tt>

 Subclasses *must* implement this method.

 Called from TWiki::Users. See the documentation of the corresponding

 method in that module for details.

 ---++ ObjectMethod *eachMembership* <tt>($cUID) -> TWiki::ListIteratorofgroupsthisuserisin</tt>

 Subclasses *must* implement this method.

 Return an iterator over the names of groups that $cUID is a member of.

 Subclasses *must* implement this method.

 ---++ ObjectMethod *isAdmin* <tt>($user) -> $boolean</tt>

 True if the user is an administrator. Default is *false*

 ---++ ObjectMethod *isAdmin* <tt>($cUID) -> $boolean</tt>

 True if the user is an administrator.

 ---++ ObjectMethod *isInGroup* <tt>($user,$group,$scanning) -> bool</tt>

 Called from TWiki::Users. See the documentation of the corresponding

 method in that module for details.

 ---++ ObjectMethod *isInGroup* <tt>($cUID,$group) -> $bool</tt>

 Default is *false*

 Test if the user identified by $cUID is in the given group. The default

 implementation iterates over all the members of $group, which is rather

 inefficient.

 Returns an empty list by default.

 ---++ ObjectMethod *getEmails* <tt>($name) -> @emailAddress</tt>

 ---++ ObjectMethod *getEmails* <tt>($user) -> @emailAddress</tt>

 If $name is a cUID, return that user's email addresses. If it is a group,

 If this is a user, return their email addresses. If it is a group,

 By default, returns the empty list.

 ---++ ObjectMethod *setEmails* <tt>($cUID,@emails)</tt>

 ---++ ObjectMethod *setEmails* <tt>($user,@emails)</tt>

 Set the email address(es) for the given user.

 Set the email address(es) for the given user. Does nothing by default.

    * =$wikiname= - wikiname to look up

 Called from TWiki::Users. See the documentation of the corresponding

 Return a list of canonical user names for the users that have this wikiname.

 method in that module for details.

 Since a single wikiname might be used by multiple login ids, we need a list.

 Subclasses *must* implement this method.

 Note that if $wikiname is the name of a group, the group will *not* be

 expanded.

 Subclasses *must* implement this method.

 ---++ ObjectMethod *checkPassword* <tt>($userName,$passwordU) -> $boolean</tt>

 Finds if the password is valid for the given user.

 ---++ ObjectMethod *checkPassword* <tt>($login,$passwordU) -> $boolean</tt>

 Finds if the password is valid for the given login. This is called using

 a login name rather than a cUID because the user may not have been mapped

 at the time it is called.

 ---++ ObjectMethod *setPassword* <tt>($user,$newPassU,$oldPassU) -> $boolean</tt>

 ---++ ObjectMethod *setPassword* <tt>($cUID,$newPassU,$oldPassU) -> $boolean</tt>

 returns undef if no error 9the default)

 returns undef if no error (the default)

 ---++ ObjectMethod *ASSERT_IS_CANONICAL_USER_ID* <tt>($user_id) -> $boolean</tt>

 Used for debugging to ensure we are actually passing a canonical_id

 ---++ ObjectMethod *ASSERT_IS_USER_LOGIN_ID* <tt>($user_login) -> $boolean</tt>

 Used for debugging to ensure we are actually passing a user login

 ---++ ObjectMethod *ASSERT_IS_USER_DISPLAY_NAME* <tt>($user_display) -> $boolean</tt>

 Used for debugging to ensure we are actually passing a user display_name

 (commonly a WikiWord Name)

 Returns true by default.