Kind: captions
Language: en
what was the origin story of C++ you you
basically gave a few perspectives of
your inspiration of object-oriented
programming that's you had a connection
with C and performance efficiency was an
important thing you were drawn to
efficiency and reliability reliability
you have to get both what
what's reliability i I really want my
telephone calls to get through and I
want to quality if what I am talking
coming out at the other end the other
end might be in London or wherever so
and you don't want the system to be
crashing if you're doing a bank here is
you must crash it might be your your
bank account that is in trouble
there's different constraints like in
games it doesn't matter too much if
there's a crash nobody dies and nobody
gets ruined but I am interested in the
combination of performance partly
because of sort of speed of things being
done part of being able to do things
that is necessary to do to have reliable
energy of larger systems if you spend
all your time interpreting a simple
function call you are not going to have
enough time to do proper signal
processing to get the telephone calls to
sound right either that or you have to
have 10 times as many computers and you
can't afford your phone anymore it's a
ridiculous idea in the modern world
because we have solved all of those
problems I mean they keep popping up in
different ways as we tackle bigger and
bigger problems so efficiency remains
always an important aspect but you have
to think about efficiency not just as
speed but as an enabler two important
things and one of the things it enables
is
this reliability is dependability you
won when I press the pedal the brake
pedal of a car it is not actually
connect it directly to to anything but a
computer that computer better work let's
talk about reliability just a little bit
so modern cars have ECU's millions of
lines of code today so this is certainly
especially true of autonomous vehicles
where some of the aspects of the control
or driver assistance systems that steer
the car that keeping the lane and so on
so how do you think you know I talked to
regulators people in government who are
very nervous about testing the safety of
these systems of software ultimately
software that makes decisions that could
lead to fatalities so how do you how do
we test off our systems like these first
of all safety like performance and like
security is a systems property people
tend to look at one part of a system at
a time and saying something like this is
secure that's all right I don't need to
do that yeah that piece of code is
secure I'll buy your operator right if
you want to have reliability if you want
to have performance if you want to have
security you have to look at the whole
system I did not expect you to say that
but that's very true
yes I'm dealing with one part of the
system and I want my part to be really
good but I know it's not the whole
system furthermore if making an
individual part perfect may actually not
be the best way of getting the highest
degree of reliability and performance
and such the steamer says see from
France type say not type safe you can
break it sure I can break anything that
runs on a computer I may not go through
your type system
if I wanted to break into your computer
I'll probably try ask you an injection
it's very true if you think about safety
or even reliability at a system level
especially when a human being is
involved it's starts becoming hopeless
pretty quickly in terms of proving that
something is safe to a certain level
yeah there's so many variables it's so
complex well let's get back to something
we can talk about and it actually makes
some progress on yes we can look at C++
programs and we can try and make sure
they crash this often the way you do
that is largely by simplification it is
not the first step is to simplify the
code have less code have code that are
less likely to go wrong it's not by
runtime testing everything
it is not by big test frameworks that
you're using yes we do that also but the
first step is actually to make sure that
when you want to express something you
can express it directly in code rather
than going through endless loops and
convolutions in your head before it gets
down the code that if if the way you are
thinking about a problem is not in the
code there is a missing piece that's
just in your head and the code you can
see what it does but it cannot see what
you thought about it unless you have
expressed things directly when you
express things directly you can maintain
it
it's these years who find errors is
easier to make modifications it's
actually easier to test it and lo and
behold it runs faster
and therefore you can use a smaller
number of computers which means there's
less hardware that could possibly break
so I think the key here is
simplification but it has to be to use
the Einstein code as simple as possible
and no simpler not simpler well there
are other areas with under constraints
where you can be simpler than you can be
in C++ but in the domain and dealing
with that's the simplification I'm after
you