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Hello guys.

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So we are going to continue the discussion with respect to Python.

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And in this video we are going to talk about encapsulation and abstraction.

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Now this will be two videos.

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In this specific video we will dedicatedly discuss about encapsulation.

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And then in the next video we will talk about abstraction uh encapsulation and abstraction.

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They are very important concepts in object oriented programming.

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And it will be helpful to design a very good, maintainable and reusable code whenever we define all

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these things and use all these things in a project.

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Okay, so if I probably go ahead and read this here, you can see an encapsulation involves bundling

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data and methods that operate on the data with a single unit, while abstraction involves hiding complex

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implementation details and exposing only the necessary feature.

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Okay, so abstraction involves hiding complex implementation detail and exposing only the necessary

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feature.

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So we will be discussing more about this in the next, uh, session because there will be specifically

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discussing about abstraction.

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But if I talk about encapsulation, it is nothing.

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But it is a concept of wrapping data, variables and methods together as a single unit.

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It restricts direct access to the same object.

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Sorry to some of the object components, which is a mean of preventing accidental inference and misuse

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of data.

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Now what does this basically mean?

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Restrict direct access to some of the object components.

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And here we are basically saying hey, it is a concept of wrapping data that is variables and methods

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together as a single unit.

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So let me just go ahead and show you some of the example over here.

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And as I said in this video, we're just going to talk about encapsulation.

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And in the next video we'll talk about uh, the next part that is abstraction okay.

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So encapsulation we can do with something called as getter and setter method.

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Okay.

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Now before I go ahead and make you understand about getter and setter method, let me just go ahead

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and talk about three important access variables.

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One is public okay.

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And I hope you may have seen this in other programming language in C sharp in C plus plus.

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So public protected and private variables okay.

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We'll talk about this.

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What exactly it is okay.

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Now let's go ahead and do one thing guys.

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If I'm going to create a class let's say I'm going to create a class called as person okay.

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And let me just go ahead and write definition in it.

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Definition.

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This is my constructor here I'll take self name and age okay.

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Okay.

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Now here you can see that if I go ahead and write self dot underscore underscore name.

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Okay.

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Uh or just let me write self dot name is equal to name okay.

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This variable or this instance variable that we are actually creating.

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This is basically called as public variables okay.

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Public variables okay.

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This instance variable or public variable I'll talk about it.

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Why we say it as public variable.

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And similarly if I go ahead and define this self dot age is equal to age.

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This is also a public variable.

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This basically means I can I can call this or I can use this particular variable from outside of this

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specific class.

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Okay.

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That basically means okay let's go ahead and see I will go ahead and define person person.

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And here I will just say hey the name is crush and here the name is age is 34.

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Okay.

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Now when I say public variable public access modifier, also I can say see I can also call this as public

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access modifiers.

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You know we'll also discussing about protected and private access modifiers okay.

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We can also talk like that.

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Variables or access modifiers okay.

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Now here you can see that there is one very important statement.

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It restricts a direct access to some of the object components.

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Here if I go ahead and print okay person dot name okay I will be able to print it okay.

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Here I'm able to get crushed.

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Now let's see if I go ahead and use this person okay.

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And if I try to understand inside this objects what are the different different inbuilt methods or variables

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that are probably available over here.

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So if I go ahead and use this Dir function and if I just go ahead and execute it here, you'll be able

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to see hey.

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And here this is what we use right.

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Definition underscore underscore init.

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This is a constructor.

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So here also you'll be able to find this method is there okay.

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And along with this you'll also be seeing there'll be two more variables that are available.

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That is age and name.

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Right.

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And these are nothing.

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But these are my public variables.

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Right.

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Or instance variables, uh, which is specifically over here at public.

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What the reason why I'm saying it as public.

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Because here you can see that I'm able to see this particular variables directly over here.

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Okay.

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And I can use it from anywhere of the program just by using the object.

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I can use it in different functions anywhere I want specifically.

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Okay.

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Uh, uh, now, one thing that you can probably do it right, I can see I can probably create a function.

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I can, uh, go ahead and write, get underscore name, and I can give the object over here, let's

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say person.

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And I can go ahead and return something like this.

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Return person dot um person dot name.

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Okay.

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And I will go ahead and execute this okay.

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Now let me just go ahead and print this.

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So here if I go ahead and write get underscore name.

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And if I just call it uh with respect to this particular person here, you can see that I'm able to

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access this particular name from outside the function outside the class itself.

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Right.

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Now, there may be scenario where I may want to define some of the variables in such a way that outside

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this class, I should not be able to provide it as an access.

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Okay.

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Because this may be some very important variables.

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Right.

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And those variables, I don't want to change it once we are initializing it, we don't really want to

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change it in the later stages.

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Okay.

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If you want to just change it, we should only be able to change it while we are creating the object.

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Right?

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And I don't want this particular variable to be as an access over there.

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Right?

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So that is the reason why what we do is that we use something called as protected and private variables.

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Now let me just show you one example of creating a private variable.

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Right now, if I just go ahead and see directory of person, I'll be able to see all these variables

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are publicly available.

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Now I will just go ahead and copy the same thing.

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Let's see this okay I will I will just go ahead and copy this I'll paste it over here.

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Okay.

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Um, now instead of just writing underscore underscore innit.

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See, I'm creating a person class.

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I'm using name and comma age as a parameter while I'm giving it over here.

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Now, instead of writing like this, I will use double underscore okay, double underscore name.

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And here also I will go ahead and use double underscore age.

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Now what is this double underscore name.

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This becomes a private variable.

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If you want to define a private variable I have to write double underscore.

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And here also I will go ahead and write the private variable as double underscore.

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Okay.

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Now if I go ahead and execute this okay.

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Now see see focus over here.

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Okay I'll remove all this particular code okay.

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And let me do one thing.

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Let me just go ahead and execute this particular code okay.

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And let me just create an object.

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So I will go ahead and create an object.

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And here I will write person person.

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And let me just go ahead and give my values crush Chris and 34.

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Okay.

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And let me just make this spelling curse.

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Correct.

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So it should be person.

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Okay.

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Now if I go ahead and check d I r with respect to this particular person.

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Now see here you can see that I'm not able to see this particular variable right.

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Do you see this or let me do one thing.

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Let me just create one more public variable along with this.

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So here I will go ahead and write self dot um name age.

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Let me just go ahead and say that gender okay.

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So gender is equal to I will go ahead and assign this particular gender variable which I'm actually

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providing over here.

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Okay.

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Let's say that this information now here you can see this is a public variable.

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And this is a private variable.

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Why I'm saying it as a private variable.

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Because I'll just tell you in some time okay.

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Now let's go ahead and update it over here.

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And let's say that I'm writing this is mail.

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Okay.

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If I go ahead and execute it here you can see directory of person.

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Okay.

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Uh it takes three positional argument but four were given uh three.

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One is name age and uh self dot gender is equal to gender.

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Let's see why this is an issue over here.

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Self dot gender is equal to gender okay I did not execute this.

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Maybe okay.

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Now it should work right now Here you can actually see that I am able to see this particular public

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variable.

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Not I'm not able to see all this underscore name on underscore age below this.

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Right.

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I'm not able to see it.

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Why.

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Because that is a private variable.

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And wherever private variable will be displayed it will be displayed over here in this format.

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Right.

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So here you can see when I write underscore person underscore underscore age, the private variable

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basically becomes in this particular way right.

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It will get appended along with the person class.

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Right.

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So I'm not getting this direct variable.

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Any underscore underscore age is no way present.

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So this basically indicates that this is a private variable okay.

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Now let me do the same thing.

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Let me just go ahead and create a function.

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And let me say hey get underscore name.

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And here I'm actually going to write uh uh I'm going to give an object called as person.

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And I'm just going to say return return person person dot underscore underscore name.

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Okay.

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I'm just going to return this.

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Now let me do the same thing over here okay.

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Let me just copy this entire thing.

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Let me call this person and let me just go ahead and call this particular function name get underscore

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name okay.

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And if I go ahead and see this and if I just give this particular parameter will I will I will will

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the name get printed.

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The answer is no.

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Why.

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Because it is saying that hey it it has no attribute underscore underscore name.

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The reason is very simple because this is a private variable and you will not be able to access this.

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You will definitely not be able to access it.

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Because if I go ahead and see inside the directory I am able to see that, hey my person, uh, the

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underscore underscore age has been in this particular name, right?

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Yes.

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In this directory you're able to see.

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But as a developer you are able to see.

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But as a common person you will not know that, hey, my private variable has got converted in this

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particular name.

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Right?

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And that is the reason you are not able to access it.

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So here we are restricting right?

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What happens with the help of access modifiers or encapsulation?

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We are restricting some of the variables because I don't want anyone to see this particular variable

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or directly access this variable, because these are some very important attributes in a class which

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I should not be changing frequently.

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Yes, as a developer, I can definitely see it.

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I what I can do, I can just go ahead and copy this and I can print it over here.

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Okay.

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I can do that as a developer.

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But this is not a good practice.

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The reason we create a private variable, because it is saying to your fellow developers, hey, this

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is a private variable and it should always be remaining hidden.

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Now if I go ahead and execute like this, I'll be able to get the answer right.

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I'll be able to get a 34 right?

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Or if I want to probably display the name, I will be able to get this particular name right.

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But if I directly call with underscore underscore name, it will not be possible because I'll be getting

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that particular error right.

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So what does private variable basically say?

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That a private variable cannot be accessed from outside the class.

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Very simple.

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It cannot be accessed from outside the class.

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Can we access it inside the class?

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Yes, we can do it.

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And for that only will be using getter and setter method.

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Right.

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So private variable is something like which you cannot access outside the class.

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Even you have a derived class that can also not access it.

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Okay.

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So this is one of the very important property in encapsulation.

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And this is where we discuss about private and protected public variable.

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There is also one more variable which is called as protected.

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How do I define protected.

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So protected is nothing.

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But I will use the same thing.

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And let's say instead of writing double underscore, I'll just write single underscore.

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So this is what a protected variable is like, right?

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A protected variable or access modifier is like okay, a protected variable basically says that, hey,

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you cannot use it outside the class.

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Like outside the class basically means we cannot access this underscore name outside the class, okay.

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But we can access it from a derived class.

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So let me just go ahead and write.

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Let's say if I go ahead and say employee is my another class okay.

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Employee is my another class.

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And if I say hey this is inheriting person.

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So here I have created a class employee which is inheriting person.

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Now what I'm actually going to do, I'll just go ahead and write my init function.

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Right.

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00:12:50,000 --> 00:12:53,000
So here I'm again going to write my init function.

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And inside this particular init function I'm just going to pass all the parameters like let's say age,

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gender.

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Okay.

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And what I'm actually going to do over here, I'll go inside this.

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And now I'm going to just write super Dot.

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And since I'm inheriting all the attributes from the upper class.

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So I will just go ahead and write this self comma name comma h comma gender okay.

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Now here you'll be able to see that, uh, if I have this class employee right Right, I should be able

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to access this particular values.

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Okay.

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Uh, and that is what protected variable is all about, right?

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Whenever we create a protected variable in one of the classes, only its derived class will be able

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to access it.

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Other than that, you won't be able to access it outside that particular class.

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Okay, so once I probably create this derived class now from this derived class, I should be able to

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access all these variables.

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So what I will do, I will just remove all these things Okay.

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I will not be requiring over here.

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Now let me just go ahead and create my employee.

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Okay.

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And here I'm going to define my employee okay.

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And let's say that I'm going to give some values like crush or 34.

282
00:13:58,000 --> 00:14:02,000
And here I'm going to give the gender as male okay.

283
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Now I will just go ahead and print employee dot underscore name.

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Right.

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00:14:10,000 --> 00:14:14,000
So once I execute it here okay five parameters is required.

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So let's see which all parameters name age gender.

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Uh over here I'm given name age gender.

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And here you will be able to see that uh underscore name underscore age.

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Um, it takes four positional arguments but five were given.

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00:14:30,000 --> 00:14:31,000
Let's see where it is.

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Four.

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Five were given.

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Uh, so self is over here.

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00:14:36,000 --> 00:14:36,000
Employee.

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00:14:36,000 --> 00:14:38,000
Person is over here.

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00:14:38,000 --> 00:14:39,000
Employee is over here.

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And this is nothing but employee dot underscore name.

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00:14:43,000 --> 00:14:46,000
Okay guys one mistake that I have done over here I've used self keyword.

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00:14:46,000 --> 00:14:48,000
So I should not be using this now.

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00:14:48,000 --> 00:14:50,000
I think it should be displaying it okay.

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00:14:50,000 --> 00:14:56,000
So employee dot underscore name here you'll be able to see that I'll be able to get this particular

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00:14:56,000 --> 00:14:57,000
output.

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00:14:57,000 --> 00:15:04,000
So in the case of whenever we define a protected variable it is it it is just like so it is not anything

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is compulsory in Python.

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00:15:05,000 --> 00:15:11,000
You know, it is uh, like a very uh, it is a kind of programming language where there are no strict

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00:15:11,000 --> 00:15:14,000
rules, but most of the concepts that we learn.

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00:15:14,000 --> 00:15:14,000
Right.

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Let's say that if I'm trying to create a private variable, if I'm trying to create a protected variable

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00:15:18,000 --> 00:15:23,000
in case of protected variable, I have to always make sure that this variable will only be accessible

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only from the derived class.

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In the case of private variable, nothing should be accessible outside the class, you know, and public

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00:15:29,000 --> 00:15:33,000
variable is what you should be able to see that you will be able to access it from anywhere, right?

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00:15:33,000 --> 00:15:38,000
So here I have actually shown you the example of all these things, uh, with respect to private variable,

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00:15:38,000 --> 00:15:40,000
with respect to public variable and all.

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00:15:40,000 --> 00:15:46,000
And uh, let's say that if I am creating a private variable, if I'm not able to access it from outside

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00:15:46,000 --> 00:15:50,000
the class, can we access it from methods that are present inside the class?

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00:15:50,000 --> 00:15:50,000
Okay.

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00:15:50,000 --> 00:15:53,000
And that is what, uh, we are basically going to do now.

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00:15:53,000 --> 00:15:54,000
Okay.

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00:15:54,000 --> 00:15:58,000
And, uh, we are going to learn encapsulation with the help of getter and setter method.

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00:15:58,000 --> 00:16:04,000
So let's go ahead and write encapsulation with getter and setter okay.

322
00:16:05,000 --> 00:16:09,000
Now what I am actually going to do over here is that, uh, first of all I'm just going to create my

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class.

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00:16:10,000 --> 00:16:15,000
So let me just go ahead and write class person and this will be definition init underscore underscore.

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00:16:15,000 --> 00:16:19,000
And here I'm going to basically write self name age okay.

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00:16:20,000 --> 00:16:23,000
And here you can see self dot underscore underscore name.

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00:16:23,000 --> 00:16:26,000
So this will basically be my private variable I will go ahead and initialize it.

328
00:16:26,000 --> 00:16:31,000
Private access modifier or variable okay.

329
00:16:31,000 --> 00:16:33,000
Or variable or variable.

330
00:16:34,000 --> 00:16:35,000
Okay.

331
00:16:35,000 --> 00:16:37,000
And uh, see it is very simple.

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00:16:37,000 --> 00:16:40,000
I need to probably not display this anywhere.

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00:16:40,000 --> 00:16:42,000
It should be restricted within the class itself.

334
00:16:42,000 --> 00:16:43,000
That is what is my aim.

335
00:16:44,000 --> 00:16:48,000
Right then I have self underscore age which will be equal to age itself.

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00:16:48,000 --> 00:16:52,000
And here I'm going to probably say that this is also my private variable.

337
00:16:52,000 --> 00:16:53,000
Okay.

338
00:16:53,000 --> 00:16:58,000
Now in order to access this particular variable inside the class I can definitely do it.

339
00:16:58,000 --> 00:17:03,000
And for this we'll be using something called as getter method for name.

340
00:17:03,000 --> 00:17:03,000
Okay.

341
00:17:03,000 --> 00:17:07,000
So we'll go ahead and create one function which is called as get underscore name.

342
00:17:07,000 --> 00:17:09,000
And here we're going to use the self keyword.

343
00:17:09,000 --> 00:17:14,000
And with the help of this self keyword wherever we use we should be able to access the underscore underscore

344
00:17:14,000 --> 00:17:15,000
name.

345
00:17:15,000 --> 00:17:19,000
So here I'm going to return self dot underscore underscore name okay.

346
00:17:19,000 --> 00:17:23,000
So this is basically my getter method for name right.

347
00:17:23,000 --> 00:17:28,000
So here you can see that I will just be exposing this particular method to the outside world.

348
00:17:28,000 --> 00:17:30,000
Because this is a public method right.

349
00:17:30,000 --> 00:17:32,000
I will not be exposing underscore underscore name.

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00:17:32,000 --> 00:17:36,000
With the help of this particular method I should be able to get this right.

351
00:17:36,000 --> 00:17:39,000
Now here is what I will talk about.

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00:17:39,000 --> 00:17:40,000
One very important thing right.

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00:17:40,000 --> 00:17:42,000
Have you seen a washing machine.

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00:17:42,000 --> 00:17:47,000
So if I am probably working on the washing machine in washing machine will be able to see buttons,

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00:17:47,000 --> 00:17:51,000
will be able to see how to start, will be able to see that where we need to put the clothes right.

356
00:17:51,000 --> 00:17:55,000
But internal working is completely hidden, right?

357
00:17:55,000 --> 00:17:56,000
And that is what over here.

358
00:17:56,000 --> 00:17:58,000
Same thing we are doing.

359
00:17:58,000 --> 00:18:00,000
The internal things are probably hidden over here.

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00:18:00,000 --> 00:18:02,000
Only the things that matter to us.

361
00:18:02,000 --> 00:18:06,000
You know, just like the function name is available for us or visible to us.

362
00:18:06,000 --> 00:18:07,000
Right?

363
00:18:07,000 --> 00:18:11,000
So here you can see that just by calling this particular method get underscore name, I should be able

364
00:18:11,000 --> 00:18:15,000
to get the uh name itself uh, from this particular function.

365
00:18:15,000 --> 00:18:17,000
This is called as a getter method.

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00:18:17,000 --> 00:18:21,000
I may also have setter method setter method for name.

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00:18:21,000 --> 00:18:23,000
Right now this setter method for name.

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00:18:23,000 --> 00:18:30,000
What it does is that this will help us to change any values that I give to the name.

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00:18:30,000 --> 00:18:34,000
The name, which is basically a private variable right over here.

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00:18:34,000 --> 00:18:35,000
So this is my private variable.

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00:18:35,000 --> 00:18:39,000
I need to probably change that particular value, let's say.

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00:18:39,000 --> 00:18:41,000
So I can just use self underscore.

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00:18:41,000 --> 00:18:43,000
Underscore name is equal to name right.

374
00:18:43,000 --> 00:18:45,000
So with the help of getter we are retrieving the data.

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00:18:45,000 --> 00:18:49,000
With the help of setter we are changing the name itself okay.

376
00:18:49,000 --> 00:18:55,000
Similarly let's say that uh uh I, I want it for the age.

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00:18:55,000 --> 00:19:00,000
And uh, uh, I can also do that, uh, you know, and probably use a getter method for that and setter

378
00:19:00,000 --> 00:19:01,000
method for that.

379
00:19:01,000 --> 00:19:04,000
So first I will do create a getter method okay.

380
00:19:04,000 --> 00:19:09,000
And here you can see I'm getting the age just writing self dot underscore age.

381
00:19:09,000 --> 00:19:15,000
And now in the case of setter method uh let's say that I want to probably put or change any age.

382
00:19:15,000 --> 00:19:15,000
Right.

383
00:19:15,000 --> 00:19:17,000
So what I do I first of all check the condition.

384
00:19:17,000 --> 00:19:20,000
If age is greater than zero, then only I will go ahead and change it.

385
00:19:20,000 --> 00:19:23,000
Otherwise I'll say age cannot be negative, right?

386
00:19:23,000 --> 00:19:26,000
So this is just one example with encapsulation with uh, getter and setter.

387
00:19:26,000 --> 00:19:30,000
And we are completely hiding the main variables that we have.

388
00:19:30,000 --> 00:19:30,000
Right.

389
00:19:30,000 --> 00:19:32,000
And we are only exposing this particular functions.

390
00:19:32,000 --> 00:19:34,000
That is get underscore name and setter underscore name.

391
00:19:35,000 --> 00:19:36,000
Now let me do one thing.

392
00:19:36,000 --> 00:19:39,000
Let me just go ahead and call all this functions okay.

393
00:19:39,000 --> 00:19:41,000
And then you'll be able to understand.

394
00:19:41,000 --> 00:19:43,000
First of all I'll go ahead and create an object.

395
00:19:43,000 --> 00:19:44,000
Let's say this will be person.

396
00:19:44,000 --> 00:19:47,000
And here I'm going to use crush.

397
00:19:47,000 --> 00:19:49,000
Here I'm going to use 34 okay.

398
00:19:50,000 --> 00:20:04,000
Now you will be able to see here what I'm actually going to do is that access and modify private variables

399
00:20:04,000 --> 00:20:08,000
using getter and setter okay.

400
00:20:08,000 --> 00:20:13,000
This is what we are going to do because obviously we cannot use directly the private variable outside

401
00:20:13,000 --> 00:20:13,000
the class.

402
00:20:13,000 --> 00:20:14,000
Right.

403
00:20:14,000 --> 00:20:19,000
So here I'm going to just print person dot get underscore name.

404
00:20:19,000 --> 00:20:23,000
So if I want to go ahead and display get underscore name I should be able to display it.

405
00:20:23,000 --> 00:20:29,000
Then if I go ahead and print person dot get underscore age.

406
00:20:29,000 --> 00:20:31,000
So I should be able to get that also.

407
00:20:32,000 --> 00:20:37,000
And then I will just go ahead and write person dot set underscore h.

408
00:20:37,000 --> 00:20:40,000
And here I'm going to basically write 35.

409
00:20:40,000 --> 00:20:40,000
Right.

410
00:20:40,000 --> 00:20:47,000
And then I'm going to print uh person dot get age again get underscore age.

411
00:20:47,000 --> 00:20:50,000
So I should be able to see the age now okay.

412
00:20:50,000 --> 00:20:51,000
Yeah.

413
00:20:51,000 --> 00:20:57,000
And then I will go ahead and set the age let's say to minus five so that I get the other error that

414
00:20:57,000 --> 00:20:58,000
I have actually written.

415
00:20:58,000 --> 00:21:04,000
Now, initially I'm creating an object, then I'm probably displaying the name displaying the age.

416
00:21:04,000 --> 00:21:06,000
So crush and 34 will be the answer.

417
00:21:06,000 --> 00:21:09,000
Then when we set the age then it will get replaced with 35.

418
00:21:09,000 --> 00:21:11,000
And then we can actually see this right?

419
00:21:11,000 --> 00:21:12,000
So crush 34.

420
00:21:12,000 --> 00:21:17,000
Then we uh, you can see over here is that, uh, what we are doing?

421
00:21:17,000 --> 00:21:21,000
We have we are printing uh, you are setting this age and then you are printing that particular age.

422
00:21:21,000 --> 00:21:26,000
And then when you are setting it to minus five, you can see that it is showing age cannot be negative,

423
00:21:26,000 --> 00:21:27,000
right.

424
00:21:27,000 --> 00:21:31,000
So this is, uh, what is all about encapsulation.

425
00:21:31,000 --> 00:21:36,000
We have discussed about all the access modifiers like public, private and public, uh, public, private

426
00:21:36,000 --> 00:21:37,000
protected.

427
00:21:37,000 --> 00:21:41,000
You understood that, uh, private variables cannot be accessed outside the class, you know?

428
00:21:41,000 --> 00:21:43,000
So that is the reason we create getter and setter method.

429
00:21:43,000 --> 00:21:46,000
Public variables can be accessed much easily protected.

430
00:21:46,000 --> 00:21:49,000
Needs to be accessed only from the derived class.

431
00:21:49,000 --> 00:21:51,000
But again, in Python nothing is compulsory.

432
00:21:51,000 --> 00:21:55,000
As I showed you when I checked the dir directory of that particular object.

433
00:21:55,000 --> 00:21:56,000
Right?

434
00:21:56,000 --> 00:21:59,000
I should be able to see all the private and public variables, right?

435
00:21:59,000 --> 00:22:02,000
And with just with the help of those name, I can directly call it.

436
00:22:02,000 --> 00:22:06,000
But it is always a good practice that we should follow whenever we are implementing things.

437
00:22:06,000 --> 00:22:07,000
So yes, this was it.

438
00:22:07,000 --> 00:22:10,000
Uh, in the next video we are going to discuss about abstraction.

439
00:22:10,000 --> 00:22:11,000
Thank you.

440
00:22:11,000 --> 00:22:11,000
Take care.

441
00:22:11,000 --> 00:22:12,000
Bye bye.