$ ./eval_with_loop.t 
1..20
ok 1 - use NaServer;
ok 2 - The class isa NaServer
ok 3 - use NaServer;
ok 4 - NaServer->can('new')
ok 5 - NaServer->can('get_val')
ok 6 - A: stdout as expected (OK 500)
ok 7 - A: stderr as expected (emtpy)
ok 8 - A: exit-value as expected (0)
ok 9 - use NaServer;
ok 10 - NaServer->can('new')
ok 11 - NaServer->can('get_val')
Subroutine say_it redefined at (eval 35) line 24.

ok 12 - B: stdout as expected (OK 500)
ok 13 - B: stderr as expected (emtpy)
ok 14 - B: exit-value as expected (0)
ok 15 - use NaServer;
ok 16 - NaServer->can('new')
ok 17 - NaServer->can('get_val')
Subroutine say_it redefined at (eval 40) line 24.

ok 18 - C: stdout as expected (OK 500)
ok 19 - C: stderr as expected (emtpy)
ok 20 - C: exit-value as expected (0)