Like Tcl's uplevel() function, but not quite so dangerous.  The idea
is just to fool caller().  All the really naughty bits of Tcl's
uplevel() are avoided.

THIS IS NOT THE SORT OF THING YOU WANT TO DO EVERYDAY

=over 4

=item uplevel

 uplevel $num_frames, \&func, @args;

Makes the given function think it's being executed $num_frames higher
than the current stack level.  So when they use caller($frames) it
will actually caller($frames + $num_frames) for them.

"uplevel(1, \&some_func, @_)" is effectively "goto &some_func" but
you don't immediately exit the current subroutine.  So while you can't
do this:

   sub wrapper {
       print "Before\n";
       goto &some_func;
       print "After\n";
   }

you can do this:

   sub wrapper {
       print "Before\n";
       my @out = uplevel 1, &some_func;
       print "After\n";
       return @out;
   }

• Vitaly Lipatov

• perl-Sub-Uplevel