Re: What could make "()" a good value for boolean false?

return (); is the same as return;, which returns an empty list when the sub is called in list context and a false value when the sub is called in scalar context. On the other hand, return undef; always returns one value from the sub: undef. When that sub is called in list context, it returns a list consisting of one element (undef). Because that list has one element, when you evaluate it in boolean context, it's true! See also Perl::Critic::Policy::Subroutines::ProhibitExplicitReturnUndef.

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Re^2: What could make "()" a good value for boolean false? by morgon (Priest) on Mar 27, 2016 at 21:06 UTC
That makes sense - thanks. So is `return ();` as opposed to simply `return;` (the two behave the same) a widely accepted convention or just a matter of personal taste?	[reply] [d/l] [select]
Re^3: What could make "()" a good value for boolean false? by Anonymous Monk on Mar 27, 2016 at 21:29 UTC
So is return (); as opposed to simply return; (the two behave the same) a widely accepted convention or just a matter of personal taste? its not a convention, there are no conventions ... its extra typed chars that serve no purpose , don't see why anyone would adopt that as a style or a convention ...	[reply]
Re^3: What could make "()" a good value for boolean false? by LanX (Saint) on Mar 27, 2016 at 21:10 UTC
> (the two behave the same) no, they do the same! Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :) Je suis Charlie!}	[reply]
Re^3: What could make "()" a good value for boolean false? by ikegami (Patriarch) on Mar 31, 2016 at 02:58 UTC
I hope not, because I'm opposed to it. Sub that are expected to return a scalar shouldn't suddenly return nothing. It causes subtle problems that aren't caught by the compiler. Consider what happens if `type` suddenly returned nothing instead of `undef`: `my $h = { type => type(), name => name(), };` [download] `return ();` should be used for subs that are expected to return a list. `return undef;` should be used for subs that are expected to return a scalar. There are exceptions, of course.	[reply] [d/l] [select]