From above cert.org link ...

In list context, things are slightly more complicated. An empty list, when evaluated in a boolean condition, evaluates to false. But the value undef, when evaluated in list context, evaluates to true because it is converted to a list with the singleton value undef. Therefore, a function should not return undef if it might ever be invoked in list context.

... that very thing -- an empty list collapsing to nothing -- has caused me irritation to work around it when something is expected, even undef: by calling the offending code in scalar context. And that was/is the *only* purpose of that damn separate call. I absolutely hate context based returned values in such cases.

In reply to Re^2: Hope a subroutine will return undef by default by Anonymous Monk
in thread Hope a subroutine will return undef by default by qj1020

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