package My::Module;
use Exporter 'import';
use My::Module::Another;
our @EXPORT = ( qw/asub1 asub2 asub3/, @My::Module::Another::EXPORT );

##</code><code>##

package My::Module::Another;
use base 'Exporter';
our @EXPORT = qw/bsub1 bsub2 bsub3/;

##</code><code>##

package My::Module;
use base 'Exporter';
our @EXPORT = qw/asub1 asub2 asub3/;
use My::Module::Another;
sub import {
	warn "WARNING: Ignoring export list!" if @_>1;
	__PACKAGE__->export_to_level(1, $_[0]);
	My::Module::Another->export_to_level(1, $_[0]);
}

##</code><code>##

package My::Module;
# no "use Exporter" or "use base 'Exporter'", we're on our own!
# ...
use Carp;
our @EXPORT_FROM_PACKS = qw/ My::Module My::Module::Another /;
sub import {
	my ($class, @export) = @_;
	my ($callerpack) = caller;
	my %export = map {$_=>1} @export;
	for my $frompack (@EXPORT_FROM_PACKS) { # loop over packages
		# attempt to load that module
		eval "require $frompack; 1"
			or croak "failed to load $frompack: $@";
		# get their @EXPORT variable
		my @exps = do { no strict 'refs'; @{"${frompack}::EXPORT"} };
		for my $ex (@exps) { # loop over their exports
			next if @export && !$export{$ex};
			no strict 'refs'; # limit scope of "no strict"
			#      target function <-- source function
			*{"${callerpack}::$ex"} = \&{"${frompack}::$ex"};
		}
	}
}