use strict;
use Foo::Bar;
my $package = 'Foo::Bar';
for my $sym ( keys %{ $::{ "${package}::" } } ) {
  print "$sym\n";
}

##</code><code>##

use strict;
use Foo::Bar;
my $package = 'Foo::Bar';
{
  no strict q(refs);
  for my $sym ( keys %{ "${package}::" } ) {
    print "$sym\n";
  }
}
__END__
PI
import

##</code><code>##

package Foo::Bar;
$PI = 3.14;
__END__