This works:

sub transform {
   my ($data,$log_fh) = @_;
    
   # Localize the log filehandle so all subroutines can see it
   local *LOG_FH = $log_fh;

   ...
   foo($bar);
}

sub foo {
   my ($bar) = @_;
   print LOG_FH "Processing $bar.\n";
   ...
}
[download]

This doesn't:

sub transform {
   my $data = shift;
   local $log_fh = shift;

   ...
   foo($bar);
}

sub foo {
   my ($bar) = @_;
   print $log_fh "Processing $bar.\n";
   ...
}
[download]

The parent function transform exists in a separate file which is being required by a file that initializes the log filehandle.

Clearly the second case (localizing an indirect filehandle) forces a compile-time error since $log_fh is not a global. Is there a way to do this with an indirect filehandle or is the first method the "best-practice" way to do it? Why would you ever do it as in the perlfaq (open local $fh...)? Am I wrong for trying?

Thanks.

Update: So I should have realized creating a global filehandle at the top of the second case would fix this problem:

our $log_fh;
sub transform {
   my $data = shift;
    print $log_fh "Processing data $data.\n";
   foo("bar");
}

sub foo {
   my ($bar) = @_;
   print $log_fh "Processing $bar.\n";
}

sub main {
    open ( local $log_fh, '>', 'test.txt' ) or die "Couldn't open log 
+file\n";
    transform( "data", $log_fh );
}
main();
[download]