Guarded Command
The guarded command is the most important element of the guarded command language. In a guarded command, just as the name says, the command is "guarded". The guard is a proposition, which must be true before the statement is executed. At the start of that statement's execution, one may assume the guard to be true. Also, if the guard is false, the statement will not be executed. The use of guarded commands makes it easier to prove the program meets the specification. The statement is often another guarded command.
Read more about this topic: Guarded Command Language
Famous quotes containing the words guarded and/or command:
“Another success is the post-office, with its educating energy augmented by cheapness and guarded by a certain religious sentiment in mankind; so that the power of a wafer or a drop of wax or gluten to guard a letter, as it flies over sea over land and comes to its address as if a battalion of artillery brought it, I look upon as a fine meter of civilization.”
—Ralph Waldo Emerson (1803–1882)
“Under bare Ben Bulben’s head
In Drumcliff churchyard Yeats is laid.
An ancestor was rector there
Long years ago, a church stands near,
By the road an ancient cross.
No marble, no conventional phrase;
On limestone quarried near the spot
By his command these words are cut:
Cast a cold eye
On life, on death.
Horseman pass by!”
—William Butler Yeats (1865–1939)