Some recent nodes about inside-out objects got me thinking about how to find out about the implementation of a regular object. In particular, is there any way to find out whether an object is implemented as a hash reference or array reference: 
use strict;

package A;

sub new{
    bless {},shift;
}

package B;

sub new{
    bless [], shift;
}

package main;

my $a = A->new;
my $b = B->new;
my $c = {};
my $d = [];

print "\$a is of type: ", ref($a), "\n";
print "\$b is of type: ", ref($b), "\n";
print "\$c is of type: ", ref($c), "\n";
print "\$d is of type: ", ref($d), "\n";

__OUTPUT__
$a is of type: A
$b is of type: B
$c is of type: HASH
$d is of type: ARRAY

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of course if you do $b->{1} = 2, you will get an error. How do I find out that $a is a hash ref, while $b is a array ref?

In reply to Is there a way to find out what kind of ref an object is? by johnnywang

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