Fun fact: the Moose "Bool" datatype will accept overloaded objects, but only if they stringify to "", "0", "1" or undef. It doesn't care what they boolify to!

Other fun fact: the Mouse "Bool" datatype will accept overloaded objects, but only if they boolify to a false value.

This is why Types::Standard 1.004 abandoned trying to be compatible with Moose and Mouse's definitions of "Bool" and instead just accepts "", "0", "1" and undef, but offers a coercion from other values.

what's your point?

I believe a tied hash can override how it behaves in scalar context, so that an empty hash can return true and a non-empty hash can return false.

An overloaded object can do various tricky things with regards to how it behaves as a boolean. For example, it could die.

if ($x || $y) {
  say "Something was true. What was it?";
  say '$x' if $x;
  say '$y' if $y;
}
else {
  say "Neither was true.";
}
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It is possible for this to print "Something was true?" but not tell you what was true. This is because $x or $y could be an overloaded object returning true or false at random each time they are checked.

toby döt ink

yeah I already mentioned overload and I have to admit I didn't expect it but Tie::Hash is indeed mentioning a SCALAR method.

But those edge cases were not my point, because these are backdoors to fake behavior.

They should nevertheless be mentioned in a footnote and tested properly in an extra script.

Cheers Rolf
_{(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery FootballPerl is like chess, only without the dice}