How to Create Classes and Objects in Python! Beginner Lesson

hello and welcome back to the channel today's video will be part 8 in our introduction to python tutorial series and today's video will focus on classes and object instances of those classes so python has a functionality to group together objects with shared features into something called a class and the way you create a class in python is you just type the word class and then the most common syntax for python classes is you would use a capital first letter so a class i like to use for example is sandwich because you obviously can have a lot of different sandwiches but then you think about the things that share them and it's that they all share and it's like well they all have bread and they all have some filling and then in general they're really only two types of sandwiches there's hot sandwiches and cold sandwiches and so you can create functionality inside of this that lets you use certain functions for all the different objects just by passing in a few shared parameters so this is a little bit of python specific syntax but after you create a class you use this def underscore underscore init underscore underscore function and then you start defining parameters that get shared by all of them and the first one is always going to be self just referring to this class as the first parameter saying when you when you use self you're referring to variables inside the class so self and then we'll say every sandwich is going to have a name we'll define a bread we'll say what the filling is and then we'll use a boolean variable to say whether or not it's hot and then the next thing about classes you need to do is you need to take those variables that you just passed in so name and you need to assign them to variables inside the class so self.name is equal to name self.bread is equal to the bread parameter we're going to pass in self dot filling will be equal to filling and self dot hot we will call hot and actually like this self dot name you're actually just creating parameters to be used within the class they don't need to be the exact same parameter names as the names you passed in so like instead of this being hot i'll call it hot or not that way you can see like it this is just so that we can use it inside of our our class functionality so let's go ahead and do an example of how you would actually use um these parameters to do something inside of a class so we'll create a function called is hot and it's just the only parameter it actually needs is self because it exists inside of this class and all we're going to say is if self dot hot or not right so we're checking if it's hot or if it's not and we'll say that um because we kind of get to define this we'll say that if that uh boolean is true then it is a hot sandwich so we'll say if hot or not then what we're going to do is we're going to print self dot name which will come through as a string and then we'll add is a hot sandwich and uh if this seems silly uh just wait until we actually get to the demonstration of what this is doing and then you'll kind of see the value in this so else print and we'll say print self.name is not a hot sandwich and so we'll add some more functionality this in a minute but let me go ahead and make a a couple instances of this class so this is how you actually define objects so think of two sandwiches real quick you have a peanut butter and jelly we'll call it pb and j and to create an object that's an instance of a class you say equals to and then the class name and then you actually give it specific parameters for all of the inputs so for pb and j we're going to say pbj for name and then we'll say white for bread we'll peanut butter and jelly for filling and then we'll say false that's not a hot sandwich and just so we have a couple instances of this let's also do a blt and that's gonna also be a sandwich but then this one is gonna have a name blt it's we're gonna put it on wheat bread the filling will be bacon lettuce and tomato there's our bl and tea and then this let's say it is a hot sandwich because you fried the bacon so what the way you actually use this is hot function is you would type the instance of the class and you would say pbj dot is hot and just by being an instance of this class we have access to all the functions inside of that class so this is going to tell us if we run it pbj is not a hot sandwich okay that's pretty cool but then let's say blt dot is hot as well and in running this blt is a hot sandwich so you can see just by having two different classes with different parameter definitions we run the same code twice and get different outputs and so that's pretty cool but we can do some cooler things with it let's do another that's def and we're actually going to say we want to build the sandwich and again it's just inside the function and we already have the bread and filling so all we need for parameters is just self and let's print to build a and let's use the name here so let's say to build a plus self dot sandwich and you can see inside these functions you actually oh it's self.name you actually use self dot to use the variable inside of the function not just the name itself.name or self.bread or filling or hot or not you always use self dot before you use something inside of a class so to build a plus self.name plus sandwich and let's say let's copy a few more print statements so to build a blank and then this we want to say start with plus self dot bread and then bread and then we'll say then put self dot filling in it and then we will just say enjoy your sandwich and that's a wholesome sandwich building program but the cool thing is with what we just did we should be able to run pbj dot build we gotta spell it right pbj dot build sandwich it's right there and blt dot build sandwich and when we run this now we get pbj is not a hot sandwich blt is a hot sandwich to build a pbj sandwich start with white bread then put peanut butter and jelly in it enjoy your sandwich to build a blt start with wheat put bacon lettuce and tomato in it enjoy your sandwich so i mean this is a maybe a silly example with sandwiches but it should show right away the kind of powerful cool functionality that you can do with classes and class objects inside of python you write code once that gets shared across a number of different objects and you get to use it however you want so this is just a food based example but classes can be used for multiple enemies or multiple players in game formats you can use classes for things like buttons on apps and and look up tables and things that operate the same way over and over and over again and you have many of the different instances of them but they all kind of have shared features so this has just been a brief introduction to classes and objects but hopefully you found it helpful if you have any questions about anything that i covered today or you feel i missed something important go ahead and drop a comment and let me know about it i'll try to get back to you as soon as i can and uh if you found any of this content or anything else on the channel useful feel free to drop a like and subscribe i really appreciate it and as always thanks for checking out the channel and good luck with your code thanks bye