They also here are characteristics that exceptions that are acceptable.
Again, recall the overarching philosophy is,
do not use them to have spaghetti control structure.
Use them where they really are needed.
Well one of these places are really needed is a nuclear power plant.
You can't have your computers shut down and
all of a sudden, critical things in the power plant get turned off.
You have a radioactive accident.
You can't have on a space mission, your machine shut down.
All of the sudden you lose some enormously expensive piece of equipment.
So in those instances you have to have the ability to make sure that
your computation recovers from an error even an unanticipated error.
And if you think about the space program.
A lot of the space program stuff like Apollo mission,
some of their stuff was built with triplicate hardware and voting hardware.
So the mission would run three programs and at least two of the programs will
have to agree and that meant that there was a fair degree of redundancy.
And even if one of the machines fail, either through a hardware error or
a software error, the other two have the ability to keep the mission on track.