You're on the right track 
use Carp 'croak';
sub UNIVERSAL::AUTOLOAD {
  my($m) = $UNIVERSAL::AUTOLOAD =~ /::(\w+)$/;

  croak "Undefined subroutine &$UNIVERSAL::AUTOLOAD called"
    unless $m eq 'global';

  print "this sub really is global\n";
}

global();

{
  package foo;
  global();
}

__output__

this sub really is global
this sub really is global

[download]
Although there's the obvious caveat that the global behaviour is no longer honoured if the current package already implements AUTOLOAD and doesn't delegate to UNIVERSAL::AUTOLOAD upon failure. That and it's fairly hideous. I'd personally opt for defining a subroutine in main then just calling it the lazy way e.g 
sub main::global {
  print "this isn't quite global\n";
}

::global();
{
  package foo;
  ::global();
}

__output__

this isn't quite global
this isn't quite global

[download]
HTH

_________
broquaint

In reply to Re^2: Creating a global function by broquaint
in thread Creating a global function by Anonymous Monk

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