On the BEGIN block issue. tye and I disagree quite emphatically on that, see the discussion starting at Re (tilly) 1: Supersplit for details. Suffice it to say that I would drop that block, and move strict to after the initial declarations.

On a more important note, my does not do what vars does. Things like @ISA, @EXPORT_OK, etc need to be global, not lexical. Either move strict to after them, or else declare with vars. my simply will not work.

Thirdly your method/no method code has a lot of repeated logic in it. I would recommend replacing it by something that looks like this:

  my $self = ref($_[0]) ? shift : $default_self;
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This also allows you to move the my declarations to the first use of the variables. Stylistically I prefer this for lexicals.

For more of my philosophy on scoping see RE (tilly) 3: redeclaring variables with 'my'.