$\=$/;
use strict;
use warnings;

package Foo;

use vars qw($str);
$str = "foo str";

package main;

my $pack = "Bar::";
my $var = "str";
print "yup" if defined ${$main::{$pack}}{$var};
/::$/ and print for keys %main::
__END__
version::
Tie::
utf8::
re::
CORE::
DynaLoader::
mro::
strict::
attributes::
Bar::       <----here
Regexp::
vars::
UNIVERSAL::
Foo::
main::
Carp::
PerlIO::
IO::
Internals::
warnings::
DB::