I know this is OLD! But i want to post this example, that works 
use MooseX::Declare;
...
...
...
    has 'error_log' => (
        is => 'rw',
        isa => 'ArrayRef',
        default => sub { [] }
    );
...
...
...
    method register_error {
        shift;
        my $s_message = shift;
        return unless defined $s_message;
        $self->error_log->push ($s_message);
        return $self->error_log->length;        
    }

[download]
self->error_log->push does not work until i assign a "default" for the array.

In reply to Re^3: Using ArrayRef data members in Moose by Anonymous Monk
in thread Using ArrayRef data members in Moose by dmorgo

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