while working on a bigger piece of code I stumbled on this warning while printing on a GLOB reference:

Scalar found where operator expected at test_fhref.pl line 17, near "$self $data" (Missing operator before $data?)

Could you tell why? The code looks simple, by even a short piece of code can be dangerous for a Perl beginer ;)

use strict;
use warnings;
use feature 'say';
{
    package Test;
    sub new {
        my $class = shift;
        my $ref = shift;
        return bless \$ref, ref $class || $class;
    }
    
    sub send {
        my $self = shift;
        my $data = shift;
        use Data::Dumper;
        say Dumper $$self; # ==> $VAR1 = \*{'::$file'}; so it is a GLO
+B ref
        print $$self $data;
        #the following does not warn...
        #~ my $fh = $$self;
        #~ print $fh $data;
    }
}

open my $file, '>', 'test.txt' or die $!;
my $t = new Test($file);
$t->send("foo");
close $file;
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for those who may ask themselves "why" using such indirect access, I copy/pasted from XML::SAX::Writer:ConsumerInterface to make my own Consumer class, and the interpreter seems irritated by a simple

    sub output {
        my ($self, $data) = @_;
        print $$self $data;
    }
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