Generally, is it considered good Perl interface style for a function to accept either a file name or a handle? If so, what is the best way to implement it?

Test program follows.

use strict;

### DoFile. Test passing either a file name or a handle.
### Return the file contents.
sub DoFile {
   my $fh = shift; local $/;
   if (UNIVERSAL::isa($fh, 'GLOB') || UNIVERSAL::isa(\$fh, 'GLOB')) {
      warn "DoFile: param is a glob\n";
      return <$fh>;
   } else {
      warn "DoFile: param is NOT a glob\n";
      local *F; open(F, $fh) or die "error: open '$fh': $!";
      my $s = <F>; close(F) or die "error: close '$fh': $!";
      return $s;
   }
}

my $file = 'f.tmp';    # test file

warn "*** Case 1: pass a GLOB\n";
open(G, $file) or die "error: open $file: $!";
warn "contents: '" . DoFile(*G) . "'\n";
close(G) or die "close $file failed: $!";

warn "*** Case 2: pass a GLOB reference\n";
open(G, $file) or die "error: open $file: $!";
warn "contents: '" . DoFile(\*G) . "'\n";
close(G) or die "close $file failed: $!";

warn "*** Case 3: pass an autovivified scalar\n";
if ($] < 5.006) {
   warn "skip, perl version less than 5.006\n";
} else {
   open(my $fh, $file) or die "error: $file open: $!";
   warn "contents: '" . DoFile($fh) . "'\n";
}

warn "*** Case 4: pass an IO::File handle\n";
{
   require IO::File;
   my $fh = IO::File->new();
   $fh->open($file) or die "error: open $file: $!";
   warn "contents: '" . DoFile($fh) . "'\n";
}

warn "*** Case 5: pass a file name\n";
warn "contents: '" . DoFile($file) . "'\n";

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In reply to Function that accepts either a file name or a handle by eyepopslikeamosquito

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