If 'flag' is 1 or missing, then current object will shadow 'ob'. If
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 func‐
tion, 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
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.