Hello all,
Can somone explain why the following code has the indicated output? 
package private;
our $my_scalar = 'my scalar';
our @my_array  = qw(my array);
our %my_hash   = ( my => 'hash' );

package main;
use strict;
use Devel::Symdump;

print "ARRAYS => "
    . join(q{, }, Devel::Symdump->arrays("private")),"\n";
print "SCALARS => "
    . join(q{, }, Devel::Symdump->scalars("private")),"\n";
print "HASHES => "
    . join(q{, }, Devel::Symdump->hashes("private")),"\n";

# yields the following
__END__
ARRAYS => private::my_array
SCALARS => private::my_scalar, private::my_array, private::my_hash
HASHES => private::my_hash

[download]
Devel::Symdump aside, what I really want to know is why the SCALAR entry for any non-scalar symbol table glob return a reference to undef instead of simply undef: 
package private;
our $my_scalar = 'my scalar';
our @my_array = qw(my array);

package main;
use strict;
use Data::Dumper;

# attempt to access the ARRAY portion of a scalar
*my_scalar_glob = $private::{my_scalar};
print "ARRAY portion of a scalar glob: " 
    . Dumper(*my_scalar_glob{ARRAY});

# attempt to access the SCALAR portion of an array
*my_array_glob = $private::{my_array};
print "SCALAR portion of an array glob: " 
    . Dumper(*my_array_glob{SCALAR});


__END__
# prints the following
ARRAY portion of a scalar glob: $VAR1 = undef;
SCALAR portion of an array glob: $VAR1 = \undef;

[download]
Devel::Symdump checks defined-ness in determining whether a symbol of a certain type exists and since the SCALAR portion of an ARRAY symbol table entry returns \undef, it passes that test and assumes that $private::my_array really exists as a scalar.

This seems at least unexpected and possibly a flaw at some level but I'm way over my head as far as my knowledge of Perl innards.

I look forward to being enlightened!

-- Brian

In reply to Devel::Symdump and symbol table woes by bpphillips

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