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Okay so now let's work on the
wizard class. So let's create a
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new class that is going to be
wizard. So a wizard is a class
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associated to a spell either
fire spell or frost spell so
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the first thing we may think
that we can do is something
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like this here a wizard is
going to be associated to a
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spell okay we come back to that
later because you will see that
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there is a better way than
doing that then we should have
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a spell book right so I'm going
to have a spell book that
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should be an array and it
should be a spell array, right?
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Then we have to initialize the
spell book. So I'm just going
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to create a constructor. Here
I'm going to receive a spell
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book that should have the exact
same type here and I'm going to
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fill it. Boom. But then we have
a function to cast all the
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spells all at once. So I'm
going to call cast all at once.
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And basically it's going to
loop over the spell book. And
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for each of them so this is a
spell that should have a type
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spell we're just going to do a
spell that but hm and as you
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can see I don't have th auto
completion and there is a good
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reason for that it's because
Typescript doesn't know that
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it's really a spell okay I
could have called that I don't
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know S like this okay so for
now Typescript doesn't know at
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all what this is so that's an
issue so how to do that how to
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make a Typescript understand
that this is something that
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should be a spell but it can be
anything it can be a fire spell
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or a fraud spell when you can
actually write here that S is
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something that extends a spell
and now this is a real type
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here so this is anything that
extends a spell and now here as
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you can see I have a name and I
have the cast function. So
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that's how you can do it, okay?
And obviously you couldn't know
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how to do that, okay? But now
you're going to remember. So
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you can write things like this
in here and you're going to see
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that we will be able to write
even more complex things in
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generate types. So anyway, now
the the type S here refer to
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something that extends a spell.
So we can create the cast from
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spell book. And so here we're
supposed to receive a name okay
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so for now it's going to be a
string but later you will see
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that we will be able to
actually change this type so
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cast spell from book yes so
what we're going to do is we're
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going to try to look in the
spell book if this spell exists
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so I'm going to do a spell and
I'm going to go and look in my
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spell book if I can find
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this spell and to know if I can
find it I'm going to look at
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the spell name so if the spell
name is equal to this name then
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we will have a spell so if
there is a spell then we're
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going to cast it and if we
don't we're going to throw a
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new error and we're going to
say that you don't have this
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spell in your spell book. Like
this. Okay not bad not bad we
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are almost done technically now
we should be able to for
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example create a wizard that is
a new wizard and here we should
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be able to send an array of
spells so we're just going to
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create fire spells that should
be of type fire spells array
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like this and I'm going to
create an array like this with
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a new fire spell inside and I'm
going to create a name but I
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can directly use my fire spell
name enem here fire spell name
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and I can create for example a
fire bolt like this so I have
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an array of one fire spell and
technically I can send this to
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my wizard and now my wizard is
a wizard of type fire spell and
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I should be able to force it
okay I should able to force it
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by typing fire spell like this
and now I cannot send something
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else than a a fire spell. So if
I create for example an array
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of frost spells like this frost
spells frost spells and here
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I'm going to use the frost
spell name dot blizzard for
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example and here it's going to
be a frost spell technically I
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shouldn't be able to send
something like this and as you
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can see it's not working
argument of type frost spell
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array is not assignable to
parameter fire spell array
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because of that okay but if I
remove it now it's alright okay
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cool so now we are almost good
because there is one last thing
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that I don't really like and
it's it's it's it's this okay
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because I have set a string so
technically I can send anything
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let me give you an example if I
use cast spell from book on my
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wizard so wizard. cast spell
from book here I can send a
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string okay but what I really
would like is that if my wizard
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is of type frost spell I would
like to be able to undescend a
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frost spell name. And if my
wizard is of type fire spell, I
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would like to be able to
undescend a fire spell name.
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Okay? So since this is really
more advanced, we're going to
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do that at the very end of the
project, okay? For now we're
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going to leave that like this.
Okay? So now we're going to
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assume that for now we are
good, okay? We are able to
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create a wizard that has a very
specific type and we are able
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to create et cetera. All the
allergic seems to work so we're
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going to work on the story in
the next video. See you in the
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next one.