Flutter 11 - Mixins Video Lecture | Flutter: Build beautiful native apps in record time - App Development

hey everybody this is Brian welcome to
the 11th flutter tutorial hoping we can
wrap up classes today I'm not gonna
really cover a numerator types because
it's it's kind of a little different but
what we're going to cover today is
mix-ins let me back up when I say a
numerator type is kind of different it's
it's more or less used as a variable we
will cover these in future tutorials but
right now we're going to really cover
mix-ins so what is a mixin and why do we
need it
so says mix-ins are a way of reusing a
class's code in multiple class
hierarchies to use a mix and use with
use the whiff keyword followed by one or
more mixin names and then some examples
and I kind of wanted a better
description so a better description is
an object-oriented programming language
is a mixin is a class that contains
methods for use by other classes without
having to be the parent of those other
classes so you kind of take inheritance
as a fundamental hierarchy and you break
that and it's not really interfaces with
abstraction it's kind of like just
saying a I don't really want to use the
whole class I just want this little part
of it meaning I don't want to really
inherit it I don't want to have to be
tied to it it's kind of weird so let's
just make our new project here
and this will calculate the Sun Moon and
stars there we go
go out here mmm did my music stop I
think my music stopped yep I'm still
listening Pandora thank you for doing
that Pandora alright so back to what
we're working on here we are going to
make a car we make a concrete class
we're going to say inch doors make it
getter for this we're gonna make a black
car because my not blacks awesome and we
want to play music in our car and we're
just going to say
boom I don't know just music whatever so
hopefully we've got four doors it's a
black car and we're just gonna play some
music
alright so pretty simple class not a
whole lot to it now we're gonna make a
truck I'm gonna make this concrete as
well I'm going to say a pool as 4x4
because you need that with a truck
specially here in Michigan give this to
door we're going to stay string color
mmm
I want a mmm what color truck do I want
let's make it a red truck giant big red
monster truck and we're gonna save lloyd
honk the horn
why not so we've got a car class and
we've got a truck class now let's say we
want to make a hybrid of those we want a
jeep actually let's call an SUV
I owned a jeep for years and years I
loved it so in this we're going to
import the car class and we're going to
import the truck class I make another
concrete class called SUV and we're
going to extend the truck but this time
we're going to say with the car what the
heck what's that mean all right so let's
see what we got going on here color is
inherited as a getter and also as a
method whoo I screwed something up here
mm-hmm
see this color oh yeah that's why there
we go fix that problem
all right so our SUV here extends truck
with car mmm what does that mean well
that's interesting let's find out in
here we're going to import the SUV we're
going to say SUV Jeep equal new SUV and
let's just examine this object see what
we got going on here you can see how we
have colors doors 4x4 as a bed and honk
the horn plays the music it does all the
things that we want it to do so we can
actually say you know honk the horn Jeep
dot play the music and let's say we want
to print a number of doors and we want
to print the color let's see what
happens here so we honk the horn we play
the music we have four doors and it's
black hmm where did it get foreign black
from that's interesting well if we look
at this you can see we're extending the
truck with the car so if we look at the
car the car has four doors and it's
black so that's where it's getting that
from if we flip those around you guessed
it we're extending a car with the truck
it will now have different properties
you'll now have two doors in red so
that's really how a mixin works it can
kind of piecemeal classes together and
use the parts that you want without
really having to mess around too much
with interfaces and inheritance and
abstraction it's kind of a I'm not a big
fan of it to be brutally honest with you
because as you can see if you do things
in a specific way you can change the
outcome of what you expect like let's
flip this back to truck and flip this
back to car and then bang
so you know you really get some
unexpected results sometime now some
would argue well you know what are you
know what results to expect because of
you know the way you're ordering things
and all that let's just for giggles here
I'm actually just going to try this
let's say mmm I have no idea what to
call this industrial we're gonna make an
industrial vehicle and we literally are
just gonna copy this car class here and
we're gonna say this is what happen we
use blue and we're gonna give this like
900 doors and of course there's no way
to play music in this thing let's go
back to our SUV
it's funny I always get this viewer
feedback where everybody like we
actually like watching you make mistakes
we learn for your mistakes and like ah
you guys were so mean to me so now we're
extending the truck with the car and the
industrial equipment let's see what this
does here run this suddenly it's got
nine hundred doors and it's blue so the
problem here is that it's picking up the
last one now I'm not sure if that's
actually a standard or if it depends on
what sort of just-in-time compilation
you go through so if you get a different
vendors just-in-time compiler it may
take the first one and not the last one
so now you've got to actually account
for those and make you know functions
that do that you should actually say
string color equal I've no idea what to
make way jeep here mmm
lime green it's like the ugliest color
on the planet and then you should
actually say into doors equal and we
want three doors just because why not
we'll say it's an old jeep and one doors
messed up now suddenly we have the way
we want it but you can get some just
kind of crazy unpredictable results with
mix-ins it's not bad to use them I don't
want it to tear you from it it is an
option a lot of older programmers will
stay away from them simply because
they've liked the structure that
inheritance gives or you know they want
to know what an interfaces are I'm sorry
they want to know that they have
everything that's in the interface that
you're providing because an interface is
a contract whereas a mix-ins it's just
kind of you know Wild West you just do
what you want so I hope you found this
educational and somewhat entertaining
we're gonna continue on with dart I'm
trying to plow through these fairly
quickly because I really want to get
into flutter I really think that flutter
is going to take off for the next year
or two and I think it's gonna be a major
competitor with the other languages out
there especially things like react
native so if you found this even
bolli helpful go ahead and visit my
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