With sub rewriting, via attributes at least, you could arrange the sub to return undef: http://perltv.org/v/code-attributes presentation about code attributes by Steve B (video; via https://twitter.com/PerlWeekly). (Blame PerlMonks for links being just dead text.)

In reply to Re: 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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