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Now, let's look at something that is called visibility modifier or access modifier.

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So in Scotland, they're called visibility modifiers, and they are the key word which is used to restrict

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the use of classes, interface methods and properties in Scotland.

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So what is a visibility modifier?

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Well, was ability modifiers are the key words which are used to restrict the use of classes, interfaces,

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methods and properties in Scotland.

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And these modifiers are used at multiple places such as the class header or the method.

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Body and visibility modifiers are categorised into four different types which are public, private,

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protected and internal.

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The most common ones are public and private, and you probably have used them already, or at least

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have seen them already.

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So let's start with a public modifier.

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A public modified element is accessible from everywhere in the project.

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The public modifier is the default modifier in Scotland, so if any class interface etc is not specified

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with any access or visibility modifier, then that class or interface or and so forth is used in a public

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scope.

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So if you had nothing, then that element is automatically public.

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All public declarations can be placed at the top of the file.

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If a member of a class is not specified, then it is by default public.

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So here the same goes as for interfaces and classes and so forth.

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So let's have a look at the syntax of public modifiers.

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As you can see, you can make a class public by adding the public key word or it is automatically public

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if you don't edit, but that's generally what you can do.

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You can add the public keyword specifically state that a class or a method or a value even form a field

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variable, however, is public.

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Then the private modifier, and that's where things are could become a little more interesting.

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Private modifier allows the elements to be accessible only within the block in which properties, fields,

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etc. are declared.

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So if something is private, then it's only accessible where it is declared.

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All right.

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So the private modifier declaration does not allow access outside of the scope, and the private package

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can be accessible within that specific file.

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So if you have multiple packages and you make one package, for example private, then this one will

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not be accessible in other files.

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So, for example, if you have multiple classes and you have a package in one class and you make this

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package private, then you cannot use it in other classes which are in other files.

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All right.

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So the syntax for a private modifier?

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Well, you can have a class that is private, then you can have its properties to be private by just

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adding this private keyword, then to methods to be private.

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And and this above example, you can see that Volks and the function do something are declared as private.

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The class example is accessible from the same source file vault and fondue.

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Something are only accessible within the sample class.

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So if we now create an object of this class example, we cannot access the variable X and we cannot

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access the method to do something.

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OK?

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So they're are really only available within that same class at this class is only available within that

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same file.

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So if we use another file, this class will not be accessible and we cannot create objects of it, then

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then turn on modifier as a feature.

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And cotton, which is not available in Java and the internal modifier makes the field visible only inside

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the module in which it is implemented.

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So all fields are declared as internal, which are accessible only inside the module in which they are

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implemented.

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All right.

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So another example here, and we can see the syntax for internal modifiers, so you can use this internal

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keyword for a class, for a property.

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And also for methods and even for global variables, as you can see here.

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So then there is a keyword called open, and we need to talk about it real quick in order to understand

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the next concept.

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So in Scotland, all classes are final by default, so they can't be inherited by default.

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OK.

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It's different to other programming languages.

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For example, in Java, it's the opposite that you have to make your class final explicitly because

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all classes can be inherited from.

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So if you want to use inheritance, then you need to make the class that you want to inherit from open.

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So to make a class inheritable to other classes, you must market with the open keyword and otherwise

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you get an error here.

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Type is final, so can't be inherited.

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All right.

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So then there is the protected modifier with a class or an interface allows visibility to its class

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or subclass.

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A protected declaration when overridden in its subclass is also protected unless it is explicitly changed.

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So we're going to look at that in a bit, and the protected modifier cannot be declared at the top level.

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So packages cannot be protected.

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You can use other visibility modifiers, but you cannot use the protected modifier on packages.

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So here's an example you can see here we're using the open keyword open class base where we use this

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protected veil I, which we set to zero.

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So now we have this clause, which derives from base, so which is our derived class.

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And there we have this function.

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Get value for this method to be precise, and it returns an integer.

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And there we now return I.

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So we'll return the variable that was created in the base class because we are inheriting from it.

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We can use it, but if we weren't inheriting from it.

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So if we're in another class that's called this Class C, then we cannot use this vow.

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I.

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Then another example of a overriding of protected types.

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So here we have an open protected value.

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So now it allows us to override that value.

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OK, so now we can override it, we cannot just only use it but actually override it.

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So you can see we have another class which also inherits from base so different to the one that we had

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before.

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As you can see, this was class derived, and now we have this class called another.

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It derives from bass.

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It also has a function called get value and then it returns II.

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But on top of that, it overrides the Value II.

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So here you can see if you want to be able to write something you need to add to open keywords to it.

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So in this case, you need to open the value that we use there, the variable.

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All right now, we have another example here of the visibility modifier.

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So we have this open class space where you make it open so that we can inherit from it.

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Our other classes, like our derived class at the bottom, can inherit from it.

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So we're a that we define as automatically public because it's public by default, right?

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We didn't specifically state that it's public, but it is by default public.

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Then we create this other variable called beam and that one is private.

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So it's private to the base class.

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Then we have this protected verbal.

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See, and we make it open.

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So this one is visible to the base and it derived class, which means that the derived class in this

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case, it's called drive, but this is the case for all classes that are deriving.

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It's visible there and it's usable there.

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Then we have this internal Valda, which is visible inside the same module, which means that it is

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visible inside of the same file, pretty much.

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And then we have this protected fund, which is our function, and it's visible to the base and the

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draft class.

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So because it's protected, it's not only visible or usable in our base class, but also in our derived

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class, but not inside of our fund.

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Main.

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All right.

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And there it's not a visible.

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So here we have already arrived, plus a C, D and E of the base class are visible.

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B is not visible.

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Why is that?

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Well, because it's private, so it's only available in the base class itself.

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Protected internal and public variables, however, are visible in the draft class and then we can even

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override the value C because it's protected so it can be used in the draft class, but it's also open

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so we can override it.

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OK, this is protected, but we can override with the override.

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Key word.

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Then we have our function mate, and in there we have a base object, so we create an object of our

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base class and we create an object of our derived class.

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All right.

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So when we try to access A and D, we can access them because A.

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S public and D.

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His internal so it's visible in the same module, and we are in the same module in this example.

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And then we have base B, C and E, which are all not visible because they are protected, so they are

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only visible in the same class or in a driving class.

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All right.

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So.

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PE is a private one, so it's not going to be visible anywhere else, right, except, of course, for

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the base class.

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Then we have to value see which is protected.

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So it's not visible outside of classes that are driving and the class itself.

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And then we have the same forty four hour function.

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All right, and then we have the vault derived object.

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And here we are trying to access C, but C is not visible.

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Why is that?

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Well, because we are inheriting.

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Our values see, we're overriding the value see, but it's still going to be protected.

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So C is not visible, so this is a little bit much to digest, I can imagine.

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So no worries, but we're going to use this quite a bit.

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So we're going to use all of these visibility modifiers when we need them and most of them, we are

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going to use very sparingly, very rarely.

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So, for example, protected and internal are not used as often as, for example, the private key word.

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So we're going to use that one and step by step, they all will become natural.

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So no worries if that was a little bit much at all at once.

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But I wanted to keep it all together in one video so you can see the different rules there.