Be wary of map { bless \$_, ... } @_. I'm mostly certain that's going to cause your parameters to ->new() to get modified. Make a copy of the value and bless that instead: map { my $v = $_; bless \ $v, ... } @_

Aloo beware of ref $b and $b->isa(...). You'll get an error if $b is a reference that isn't also an object. __PACKAGE__ eq ref $b is much safer for this.