Ruby Programming Tutorial - 6 - Inheritance Video Lecture - Introduction

alright guys welcome to your sixth
lesson in guys I got some good news in
between making the last tutorial in this
tutorial I got a call from Microsoft and
it just so happens that they saw our
program and they want to pay us millions
of dollars but they just said that
instead of having one general animal
class that we actually need to have
classes for each different type of
animal a dog a cat a fish so that's nice
and also let's see if we can do that and
another thing I want to mention is this
anytime you close out of interactive
Ruby your memory gets cleared so
whenever we close out this program and
reopen it it's not going to save the
animal class so we can go ahead and
close out using this X or we can do with
the cool interactive Ruby Ruby way just
go ahead and type exit hit enter and
exits out of it I just thought I tell
you guys that so now let's go ahead and
open it again and what we want to do is
we want to work on this new program that
Microsoft wants now remember they want
us to rewrite our program so we have
classes for dogs cats and birds so
basically whenever we create classes we
can use something called inheritance now
inheritance is going to make your
program like a whole lot easier it makes
it easier to create related objects such
as dogs cats and birds since all of
these things are all animals this is
basically what we're going to do we're
going to create a general animals class
just like before now all animals have a
name and age in a trait however since
Microsoft wants a class for each one dog
cat and fish what we're going to do is
we're going to kind of steal all the
attributes from animal instead of having
to retype it each time so basically
instead of having to type the same code
over and over and over and over again if
we can just use the little trick called
inheritance it's going to save you a
whole bunch time so enough of me talking
the first thing we need to do is make a
general animals class so let's go ahead
and do that right now class animal
attr underscore accessor now we write
all of the different attributes we want
such as name and remember we don't want
any of these to be specific to a dog a
cat or a fish such as you know how fast
doesn't swim how loud does it mail we
want these to be general to all animals
such as name age and trait so these are
attributes that all animals have in
common so now let's just go ahead and
end our animal class in there we go we
get now we didn't mess up at all so now
what we need to do is we need to create
a bunch of different classes for each
type of animal say we want to create a
dog a cat in a fish class so let's go
ahead and create a dog class first class
dog now instead of hitting enter go
ahead and write the less than sign and
write animal now whenever we hit enter
and hit end check out what we just did
we created a dog class of course we did
because we got now but what we did is
instead of writing this little or line
right here attribute accessor name age
straight what we did is we inherited
everything from the animal class think
of this less sign as a arrow pretty much
means dump everything from the animal
class into the dog class so instead of
having to write all this stuff it's a
little shortcut just to basically say
okay whatever is in this animal class
dump into the dog class so even though
you can't see it right now this stock
class has the name age and trait
attributes so it saved us a little bit
of typing that's pretty much a shortcut
so now we need to do the same thing for
a cat class in a fish class so class cat
dump everything from the animal class
aka all the attributes into the cat
class and in that class okay that one
worked out good now class fish animal
and end so basically we made four
different classes a general animal class
which has named agent rate and instead
of having to rewrite that whole thing
for dog name age straight cat name a
straight fish name a straight we just
wrote it once in a general class and
inherit it into our three separate
classes so remember this each of these
classes inherit the name age and trait
from the animal class the less hand sign
lower less than sign means give the
attributes from this class to another
it's just a lot faster than typing it
out each time so say that Bill Gates
says that this animal database is an
awesome program well actually you know
I'm going to back up and I'm going to
save that for the next story because
Bill Gates he needs to take his time
think about what he really wants in this
program but anyways I'm going to be
showing you guys something really really
cool in the next video so thank you guys
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