Ruby Programming Tutorial - 7 - Adding More Attributes Video Lecture -

alright guys welcome to your seventh
tutorial and in this lesson I'm going to
show you guys how to add additional
attributes to classes aside from the
ones you inherit so say that you know we
have this program this database animal
program selling and it is selling like
hotcakes people are loving this thing
they can run this program store all of
their dogs cats and fish in this Ruby
database and a bunch of zoos are buying
it and a bunch of different pet shops
however we've been getting some
complaints that the people who store
fish they also want to store the let's
say they want to store the type of fish
is it a perch is it a goldfish is it a
bass well in order to add an additional
attribute that you can store we need to
rewrite the fish class so it's a little
bit different so let's go ahead and
rewrite this fish class so class fish
and hair everything from animal so go
ahead and hit enter
now before we end this class we need to
add an additional attribute which is
type so go ahead and write a TTR
underscore asesor type now go ahead and
hit enter and now hit end so check out
what we did just did unlike before where
we just inherited all of these
attributes name age and trait from
animal the fish class is a little bit
different with this first line means is
fish is going to inherit everything from
animal but what the second line means is
it also has an additional attribute
called type
so while dog and cat have name age and
trait the fish class is going to be able
to store name age trait and type of fish
okay simple enough now that's what I say
but do you guys really believe me buck
your Roberts you know you don't even met
me let's go ahead and test this baby out
so let's go ahead and create a fish
object and remember whenever we have an
object that's how we access the
attributes so fish
equals fish dot new basically we're
creating a new fish object from the fish
class and that's where that new keyword
comes in it's a new object so now what
we can do of course that's where it's
stored on our computer is we can give
our fish our name and age in the type so
fish name what's a good name for a fish
bubbles I got one Nemo
there we go so our fish's name is Nemo
and fish is age how old was Nemo how old
was he like three maybe I don't know
Nemo is three and let's go ahead and
give a Nemo type so a fish type what the
heck was he he was like orange and white
striped I'm just gonna say that Nemo was
a goldfish even though I know he was if
anyone knows what type of fish Nemo was
go ahead and leave me a comment in the
comment section and please let me know
so go ahead and store that and check it
out now check this out even though we
didn't give him a trait yet Nemo has a
name and age in the type now remember
the type is only specific to that fish
class a dog in the cat cannot have a
type because we only put that type
attribute in our fish class as an
additional attribute so what happens
whenever we try to give this type to
something like a dog or a cat well let's
go ahead and do that right now let's go
ahead and make a new dog object so dog
equals dog new we're making a new object
code dog and it's from the dog class and
of course it's a new object so now we
need to give this dog a name so dog name
equals Floyd now remember all of the
animals are able to have names so this
should work out properly which it does
now let's go ahead and give this dog a
trait so dog trait now remember all
animals also can have traits such as
annoying so this should work out but the
one thing that a dog can't have is a
type only fish can have type so if you
try to give this dog
type such is I don't know a hound I said
that kind of weird
I said hound a hound I meant now we go
ahead and hit enter and check it out it
says whoa whoa whoa no method err yadda
yadda yadda at this memory okay
basically it's yelling at us saying okay
you have an error because only the fish
class has the type attribute dogs can't
have types they can only have name age
entry only fish can have type because
that's an additional attribute that you
added in the fish class whenever you
made the fish class
so just remember any time you're using
an object and you give it an attribute
that it shouldn't have you're going to
get an error that looks like this so
basically we got this because only the
fish class can have the type attribute
not the dog and not the cat either so
there is your quick example on classes
creating objects inheritance and also
how to add additional attributes the
classes that need them so I know this is
a lot and guys I want to mention this if
you are feeling lost right now what I'm
going to do is I'm going to take
everything I just want to give you guys
kind of a quick example of all Ruby has
to offer but in the upcoming tutorials
I'm going to break everything up and
take things slow piece by piece by piece
and trust me stick with these tutorials
even if you're feeling lost and by the
end of this video series you guys are
going to be the best Ruby programmers
ever so I just want to give you those
words of encouragement because I know
I'm going kind of fast but trust me it
gets easier so thank you guys for
watching well last time don't forget to
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Google+ and I'll see you guys in the
next video