> It does not prevent the sub from being called with more arguments than allowed.

hmm ... you are going to extremes now. :)

so

->mutate(FIELD) is a getter for FIELD

->mutate(FIELD,VALUE) is a setter for FIELD

->mutate(FILED,VALUE,OTHER...) shouldn't compile

I think, in this particular case you can still apply a prototype of ($;$) together with the signature ($field,@values)

At least theoretically, not sure if it's still implemented that way.

UPDATE

well not with methods, see other post:

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

In reply to Re^7: Distinguish between missing and undefined arguments with subroutine signatures (semipredicate problem) by LanX
in thread Distinguish between missing and undefined arguments with subroutine signatures by jo37

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