> To my understanding it is needed for an optional value argument in a signature.

Ah ... I see. Using a slurpy parameter @settings will solve this and fits much better into your use-case.

from perlsub

After positional parameters, additional arguments may be captured in a slurpy parameter. The simplest form of this is just an array variable: 
sub foo ($filter, @inputs) {
    print $filter->($_) foreach @inputs;
}

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

In reply to Re^5: Distinguish between missing and undefined arguments with subroutine signatures (slurpy parameter) by LanX
in thread Distinguish between missing and undefined arguments with subroutine signatures by jo37

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