This is why it is generally recommended that subroutines should use return with no arguments when the intent is to return a false value --- in scalar context it returns undef, in list context it returns an empty list.
It doe not return undef in scalar context, it still returns the empty list, but that will evaluate to undef. If a sub always returns a single element, it makes no sense to use return without arguments, and return undef is much more explicitly self documenting.
If your sub normally returns a scalar, use an explicit return undef;.
If your sub normally returns a list with more than one element, use an explicit return ();.
If your sub is polymorphic, return without arguments. Or do so explicitly: return wantarray ? () : undef;.
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It doe not return undef in scalar context, it still returns the empty
list, but that will evaluate to undef.
I don't think this kind of distinction is particularly useful
--- the docs clearly state that in scalar context a bare return
returns undef ... whether that is because the empty list evaluates to
undef in scalar context or that an undef is explicitly returned is
not relevant to this discussion.
Using return without args just means: return wantwarray()? () : undef;
and if that is the behaviour you desire, using a bare return is
clear, concise, well documented, and convenient.
If your sub normally returns a list with more than one element, use
an explicit return ();.
I don't see how that is more explicit. Both return; and
return (); are exactly the same --- calling return with
no arguments --- and they both do the context sensitive polymorhpic
return (undef or empty list). Your way does not seem to me to be
more explicitly passing an empty list any more than print ();
vs print; is more explicitly passing an empty list to
the print function.