Another possibility to consider is named arguments.

Perl supports this easily by having your sub construe the argument list as "hash-like". That is, instead of     my @args = @_; you could say     my %args = @_; Then the caller could do something like

    func(
        value => $obj_value,
        object => $obj,
        top => $top_node,
        affected_objects => { .... },
    );
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With this scheme, it is easy to have any arguments be optional, rather than having to rank their "optionalness" as in the scheme I suggested above.