void set_this_object(object object_to_pretend_to_be);

This is a privleged function, only to be used in the master object or in
the simul_efun object.
It changes the result of this_object() in the using function, and the result
of previous_object() in functions called in other objects by call_other().
Its effect will remain till there is a return of an external function call,
or another call of set_this_object(). While executing code in the master
object's program or the primary simul_efun object's program, set_this_object()
is granted even if this_object() is altered by set_this_object(). This does
not apply to functions inherited from other programs.

Use it with extreme care to avoid inconsistencies.
After a call of set_this_object(), some LPC-constructs might behave in an odd
manner, or even crash the game. In particular, using global variables or
calling local functions ( except by call_other ) is illegal.

With the current implementation, global varaibles can be accessed, but this
is not guaranteed to work in subsequent versions.

Allowed are call_other, map functions, access of local variables ( which might
hold array pointers to a global array ), simple arithmetic and the assignment
operators.