Hi, welcome to this new lesson. We're going to start Week 4, where we're going
to be discovering the power of object-oriented
programming. Object-oriented programming
is a really exciting topic that I was really looking
forward to reach because it really opens up for you a whole range of techniques
and methodologies that you can use and really start
expanding much more the power of programming in Python
and other languages that use object-oriented
programming as a paradigm, really benefit from the
increasing reusability and possibilities with
code that is written in such a way. Let's learn a little bit of what object-oriented
programming means. The principle of
object-oriented programming is the idea that
you can actually construct an object through the process of creating a class. A class is an outline
of an object. As we have it here, let's
look at this diagram. We have the idea of creating
an object like a dog, and we will have
certain attributes, certain characteristics
that this dog will contain. We have the idea of a name. Maybe the species of
the dog, the age. Then there's also a
series of action, a series of maybe functions that this dog as an
object will perform, something like
barking or fetching. If we look behind the
hood of this object, we have a structure to it. We have a class
name that defines what is this class.
We have some data. As we can see from the outline, some data that is contained
within this object, and then we have a
series of functions. All of this packaged together is what we would
actually call a class, that would be, again, an
outline of an object. Let's understand how,
before we actually write, the code and
understand the syntax for how to write a class, how we can actually
make use of this class. If we have the class dog, that means that we could have perhaps maybe many
instances of this class. We can see on the
right, what we are calling an instance
of a class is in fact a construction and an entity that will
operate within our script, in our simulation,
in processing. In the case of the instance, the data that we're calling name would actually
have a specific name. You could imagine, I
don't know, Max dog. Then the species will be
a specific kind of dog, and then also a particular age. That doesn't mean that
all dogs have that age, except in this
particular instance of the dog has that age. Also, it might not be
barking all the time. It might be sometimes barking, so the function bark might be
executed at certain times. We can have, as I mentioned, multiple instances of a class. This is the power of the
reusability of a piece of code that we write as a template
for a type of object, an object that we will
actually be able to reuse. But each time we
construct a new object, in this case, a new dog, that new dog might have
different pieces of data, might have different names as we have them in the real world, different age, and so on, and they might invoke
their barking function and their fetching function
at different times. Classes are an
incredibly useful tool to think of modular
forms of programming, scalable forms of programming, where you could actually
write this code and reuse it. You could even write it in such a way that
it's completely self-packaged and you
can move it around. It really starts opening up
what we can actually do with programming and really scaling
our programming skills. I'm going to move forward to
just show you the syntax of a class and we'll start writing classes together in
the next few lessons.