#!/usr/bin/perl
use strict;
use warnings;

open my $fhout, '>', "./test_out.file" || die "$!";
&test_print($fhout);


sub test_print{
        my $fhout = @_;
        print {$fhout} "this is a test\n";
}

close $fhout;

##</code><code>##

~$ perl test_write.pl
Can't use string ("1") as a symbol ref while "strict refs" in use at test_write.pl line 11.