```{index} single: lock_hash; Hash::Util function ``` ```{index} single: Hash::Util::lock_hash; Perl function ``` # lock_hash Lock the whole hash: both its keyset and every value. ## Synopsis lock_hash(%hash); Equivalent to `lock_keys(%hash)` followed by `lock_value` on each existing key. After the call, no key may be added and no value overwritten; `delete` still works but leaves the slot as a hidden placeholder. Returns a reference to the hash.