sub get_closure {
  my ($filename) = @_;
  open my $ifh, "<", $filename or die $!;
  return sub {
      # subroutine that returns one record per call
  }
}

# and then:

my $getNextRecord = get_closure($filename);
while ( my $record = $getNextRecord->() ){
    # do something with $record
}


##</code><code>##

my $file = shift @ARGV;

my $ifh;
my $is_stdin = 0;
if (defined $file){
  open $ifh, "<", $file or die $!;
} else {
  $ifh = *STDIN;
  $is_stdin++;
}

while (<$ifh>){
   # Process
}
#close $ifh unless $is_stdin;
close $ifh;

## code passes...
## ... and
my $another_value = <STDIN>;