'b' => exists($tests{'b'}) && defined($m=$tests{'b'}) ? $m : 0,
needlessly superfulous and relies on a side effect I'm a little wary of; do:
'b' => (defined $tests{'b'}) ? $tests{'b'} : 0,
But since the default is
0, this should mitigate the need for
defined:
b => $tests{b} // 0,
Also, defined($m=$tests{'b'}) smells a little funny; I get what you're doing but it is unnecessary.
Update - I am confused but the need for $m. It's getting set twice in your original code, both times based on the state of $tests{'b'}, then you set it to 10. What are you trying to do? Is this your real code or a contrived example?
