I suspect the reason is fundamentally the same. I missed that you have references among the values of %default_values, meaning that you need a deep copy (not the shallow copy originally proposed). Try this quick fix (just to confirm the hypothesis): 

    my %default = %default_values;  # shallow copy
    $default{ AUTHOR } =
       +{ %{ $default_values{ AUTHOR } } };  # copy next level

    my $self = ref($class) ? bless( \%default, ref($class) )
                           : bless( \%default, $class );

[download]
Ultimately, my preferred code for this would be something like 
my $self = bless deep_copy( \%default_values ), $class;

[download]
where deep_copy takes a reference as argument and returns a reference to a deep copy of it.

I know that there are CPAN modules for doing deep copying, but I have no direct experience with any of them, so I can't recommend any one in particular. Maybe some other monk can.

the lowliest monk

In reply to Re^3: Wrong Error Message When Testing for Failure of Constructor by tlm
in thread Wrong Error Message When Testing for Failure of Constructor by jkeenan1

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