WEBVTT

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ok so let's take the next
step on one of the ideas

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on that we get that we had when
we implemented this model you

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controller was that we can catch
multiple use to the same model

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and all of them
automatically get updated

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through z observatiton
through the observer so

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now we're going to yeah use the
benefits of the observer pattern

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to implement this
behavior exactly so

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you still i hope so at least
 you remember the account

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of you that that we had and we
didn't change anything here

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so we have this strike at
that's what we add that

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was the last thing that we added
 because we we do this on

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typecasting here which could go
wrong because no objects this

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typecasting explicit occurs which
 could go wrong because the

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object doesn't always need
 to be something that

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can be cast into an integer and
arm so what we do know as we

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just add a couple of new use so we
 had the tiny little rectangle

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which moves along the screen yet
 and now we want to move have

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another rectangle for example
that change the color exactly

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and we prepared a
little bit here so on

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you don't have to wait until he
 slowly tried everything in

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the exact so it does
basically the same so it

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register as the if you
 with the subject

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so calls the on the observed
 that the super the

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construct of the superclass
 the of the observe

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extend also extends the observer
 on and then we just kind of

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have a new array of colors here
and then we cast again because

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the value into an end and
then we just go through

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the array is or not be
 we define and use

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we define a new color
for for each element

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and then on we kind of an and use
 them as the the the red green

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and blue all factors and feel
 direct ending with these

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countries cobb that kind of this
created from these three components

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and then we we draw we
re draw the same thing

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as before nothing new in
and then another third

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one which is displayed a number
of arm and in this case it's

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little different because
 here for example

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we can use a string
 there because

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we need a string in the end
 to display the number

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so we need also to kind of make
 this object that we pass in

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into a string and the easiest way
 to make something to string

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is to chose at an empty space
again with what we will know

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we'll call internally to
 string on the object

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and then add an empty
in active string and

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which does nothing
and yeah and in

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line number ten we update was a
string already given doesn't

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that interview
with the other

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methods like in kind of
color all condom you

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know i mean because this update
 method is an object object

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is fine and the only place
 where it would cause

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problem is where we do the
typecasting and we don't do attack

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us in the same as of
this date only cords

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this update in this class so
therefore and basically it

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might also be would
also work like this

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because then the the integer
would be turned to string in

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the same way than
 any other so

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what do we need to do we
need to say that first

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then we need to consecrate
 or them use and

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here we need to register
 them was our model

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but this is
automatically done

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more or less and less so let's
start with the so we create

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the references first
opened of you cum and

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continue number and all of
these are still observance

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and now we fifty clear or
references now we need to assigns

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values so we need to court
constructors and this is also kind

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of a basic concept in
using these design that

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answers try to use the
interface wherever possible

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because polymorphism
 is going to

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ok so that's that now

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we can control a good so
 you can digital use

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so cooking pasting is
normally hedley discouraged

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but as well
but you know

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and now we need to we
need to for the correct

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constructions
so lower case

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and please do recall that the
court has a constructor already

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registers the object with the
model exactly so the model is

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fast here the car this past year
 so that the can you use get

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registered with the model so that
should modest speed is sufficient

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so let's riots

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and there is nothing to
see it there's a counter

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onto with where the slow that's
normally in the beginning so

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nodes and warm up well the
other things are missing

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yes your crash no and
 in there must be

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let's try to try one so
within here at the number

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yeah let let's let's that
stretches to two species wrong

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and is color or what we see here
 yeah still going up yes here

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we go on color or causes
 where numbers are

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the numbers are gone let's
 have a look in two

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to use yeah you see

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it's this line so when the crawl
 method or when this is read

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from it does was
 yeah methods

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he acted method has a quarter
background tended not only draws

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the number or the rectangular but
 also the complete background

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all over and so yet first thing
 that had this everything is

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painted great and then the
moving on after rectangle

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all the number although
call-ups rectangle storm

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on top of that and then everything
 is kind of trade again and

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only the nothing sorites so so
how do we have that we remove

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that here but we will
need to have its own so

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we that's let's just see what
happens if removed everywhere

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and we have not probably
know back on the movement

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so that maybe i didn't
 like that great

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you pick sometimes
ok what happens

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yeah i would like to know
 all along with great

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for her paine's everything all
over again and that's a moving

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on this moving on and look it kind
 of leaves a trail pheromone

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so i'm going to
stop you know

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yeah we need as a we need to
background that's what we want

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to show the and we needed
just once for every frame

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yeah so we do that in
 the most clicked

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and of course that this
big project would be we

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in the in the key had this
 so you have that so

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we can just quite background
because this is where we are

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ok now let's try it
again but we haven't

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all over each other
 still but now

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yeah i mean that's that's problem
 if you put everything in

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the same place that it's
a little each other but

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it is actually const
correctly so that is

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covered by first number was cover
 and there's also the little

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rectangle moving the little moving
 rectangle you see it doesn't

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leave trail anymore so basically
 you're still trying to get

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into the and variety