#!/usr/bin/perl
use strict;
use warnings;
 
use IO::Handle;
 
my $data = 'some sample data here';
 
open my $fh, '<', \$data or die "open(): $!";
print {*STDERR} 'ref $fh yields ', ref $fh, "\n";
print_prop('$fh->can("opened")', $fh->can('opened'));
print_prop('$fh->can("seek")', $fh->can('opened'));
print_prop('$fh->can("seekable")', $fh->can('opened'));
print_prop('$fh is IO::Handle', $fh->isa('IO::Handle'));
print_prop('$fh->can("opened")', $fh->can("opened"));
print_prop('$fh->opened()', $fh->opened());
print_prop('$fh->can("seek")', $fh->can("seek"));
eval {print_prop('$fh->seek(0, 0)', $fh->seek(0, 0));} or print "$@";
print_prop('$fh is tied', tied $fh);
close $fh;
 
sub print_prop {
   my ($msg, $flag) = @_;
   print {*STDERR} $msg, '? ', ($flag ? 'yes' : 'no'), "\n";
   return;
}
 
__END__
ref $fh yields GLOB
$fh->can("opened")? no
$fh->can("seek")? no
$fh->can("seekable")? no
$fh is IO::Handle? no
$fh->can("opened")? no
$fh->opened()? yes
$fh->can("seek")? no
Can't locate object method "seek" via package "IO::Handle" at memhandle.pl line 19.
$fh is tied? no