Issue #16993 has been updated by mame (Yusuke Endoh). Given the convention of deriving methods such as `key_set` from `keys`, where the former returns a set instead of an array, one might expect a corresponding derivation like `Kernel#instance_variable_set` for `Kernel#instance_variables`. Unfortunately, this would conflict with an existing method name. ---------------------------------------- Feature #16993: Sets: from hash keys using Hash#key_set https://bugs.ruby-lang.org/issues/16993#change-112627 * Author: marcandre (Marc-Andre Lafortune) * Status: Open ---------------------------------------- To create a set from hash keys currently implies a temporary array for all keys, rehashing all those keys and rebuilding a hash. Instead, the hash could be copied and its values set to `true`. ```ruby h = {a: 1} # Now: Set.new(h.keys) # => Set[:a] # After h.key_set # => Set[:a], efficiently. ``` -- https://bugs.ruby-lang.org/