lock_ref_keys_plus

Lock the hash to the union of its current keys and a given extra list.

Synopsis

lock_ref_keys_plus($href, @additional_keys); lock_keys_plus(%hash, @additional_keys); # plain-hash form

Equivalent to lock_keys($hash, @additional_keys, keys %hash) without having to list the existing keys yourself. Extra keys that are not yet present in the hash become hidden placeholders — they are legal to assign to later but do not yet appear in keys.

Returns a reference to the hash.