#use strict;
use warnings;

sub subfunction {
    foreach my $j (0..5) {
        my $SUB = 'testsub'.$j;
        *$SUB = sub { display($j); };
    }
}

sub display {
    my $x = shift;

    print "\$x = $x\n";
}

subfunction();

&testsub0();
&testsub1();
&testsub2();
&testsub3();
&testsub4();
&testsub5();

__END__
$x = 0
$x = 1
$x = 2
$x = 3
$x = 4
$x = 5