Ceremony of the Keys (London) Ceremony of the Keys (London) The Ceremony of the Keys is an ancient ritual, held every evening at the Tower of London, when the main gates are locked for the night. It is said to be the oldest military ceremony in the world, and is the best-known ceremonial tradition of the Tower. At exactly 9.53 pm, the Chief Yeoman Warder, dressed in Tudor watchcoat and bonnet, and carrying a candle lantern, leaves the Byward Tower and falls in with the Escort to the Keys, a military escort made up of armed members of the Tower of London Guard. The Warder
Locks-and-keys Locks-and-keys Locks-and-keys is a solution to dangling pointers in computer programming languages. The locks-and-keys approach represents pointers as ordered pairs (key, address) where the key is an integer value. Heap-dynamic variables are represented as the storage for the variable plus a cell for an integer lock value. When a variable is allocated, a "lock value" is created and placed both into the variable's cell and into the pointer's key cell. Every access to the pointer compares these two values, and access is allowed only if the values match. When a variable is deallocated, the key of its pointer is modified