如何将包符号导出到Perl中的命名空间？

mod.pm

#!/usr/bin/perl

package mod;

use strict;
use warnings;

require Exporter;

@ISA = qw(Exporter);
@EXPORT=qw($a);


our $a=(1);

1;

test.pl

$cat test.pl
#!/usr/bin/perl

use mod;

print($a);

这是运行它的结果

$./test.pl
Global symbol "@ISA" requires explicit package name at mod.pm line 10.
Global symbol "@EXPORT" requires explicit package name at mod.pm line 11.
Compilation failed in require at ./test.pl line 3.
BEGIN failed--compilation aborted at ./test.pl line 3.

$perl -version
This is perl,v5.8.4 built for sun4-solaris-64int