You can get the print to work if you wrap the filehandle in a block.

my $s = {} ;
open  $s->{out}, '>', 'out' or die "open: $!\n";
print { $s->{out} } "test";
close $s->{out} or die "close: $!\n";
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Note that if you're reading from a filehandle in an array, you have to store it in a scalar for the diamond operator to work.

my $fh = $s->{in};
my $line = <$fh>;
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If that's too much trouble, you can use readline.