shadow(3)             LPC Library Functions             shadow(3)

NAME
     shadow() - shadow one or more functions in some object

SYNOPSIS
     object shadow( object ob, int flag );

DESCRIPTION
     If `flag' is 1 or missing, then current object  will  shadow
     `ob'. If `flag' is 0, then either 0 will be returned, or the
     object that is already shadowing `ob'.

     The master object defines the function "valid_shadow()".  If
     it  returns  1  the target object can't be shadowed, and the
     "shadow()" function will return 0 instead of `ob'.

     If  an  object  `a'  shadows  an  object   `b',   then   all
     "call_other(func)"  to  `b'  will  be  redirected to `a'. If
     object `a' has not defined the function, then the call  will
     be  forwarded to `b' (as if there were no shadow).  There is
     only  one  object  that  can  call  functions  in  `b'  with
     call_other(),  and  that  is  `a'.  Not  even object `b' can
     "call_other()" itself. All normal (internal) function  calls
     inside `b' will however remain internal to `b'.

     There are two ways to remove the shadow. Either destruct it,
     or  the  object  that  was shadowed. In the latter case, the
     shadow will also be destructed automatically.

     The result is that it is possible to hide an  object  behind
     another one, but everything can be totally transparent.  The
     shadow() efunction makes it possible to change the  behavior
     of  an  object  without  changing the code for the object in
     question.  One possible use for shadow() is to  add  special
     capabilities  to various classes of players (thief, fighter,
     mage, etc).  This usage would make it possible to  keep  the
     player  object much simpler than it could be if the code for
     the various classes had to be in the player object itself.

SEE ALSO
     destruct(3), shadowp(3), query_shadowing(3), valid_shadow(4)

MudOS                Last change: 5 Sep 1994                    1