Intermediate tour: Classes chapter #4564
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danil-pavlov
requested changes
Nov 25, 2024
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Huge work, maybe the most the useful content on the website
My only concern again is the size of these chapters
I think It could be three pages, for example
- Classes and interfaces 2. Objects 3. Open and other special classes
the 3rd page could be even a part of the Advanced tour
| abstract class Animal | ||
| ``` | ||
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| To declare a function **without** an implementation, you also use the `abstract` keyword: |
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Maybe it's too detailed (after all, it's an intermediate tour) and can be shortened to
To declare a function or a property without implementation, you also use the
abstractkeyword:
with one code example for both
| to define different product categories: | ||
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| ```kotlin | ||
| abstract class Product( val name: String, var price: Double ) { |
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Here and in the code blocks below, spaces are unnecessary around the class properties inside the brackets
| Although abstract classes are great for sharing code in this way, they are restricted by the fact that classes in Kotlin | ||
| only support single inheritance. If you need to inherit from multiple sources, consider using interfaces. | ||
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| For more information about abstract classes, see [Abstract classes](classes.md#abstract-classes). |
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| For more information about abstract classes, see [Abstract classes](classes.md#abstract-classes). | |
| For more information, see [Abstract classes](classes.md#abstract-classes). |
| In the example: | ||
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| * `PaymentMethod` is an interface that has an `initiatePayment()` function without an implementation. | ||
| * `PaymentType` is an interface that has a `paymentType` property that isn't initialized. |
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| * `PaymentType` is an interface that has a `paymentType` property that isn't initialized. | |
| * `PaymentType` is an interface that has the `paymentType` property that isn't initialized. |
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| In the example: | ||
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| * `PaymentMethod` is an interface that has an `initiatePayment()` function without an implementation. |
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| * `PaymentMethod` is an interface that has an `initiatePayment()` function without an implementation. | |
| * `PaymentMethod` is an interface that has the `initiatePayment()` function without an implementation. |
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| Enum classes can have properties and member functions just like normal classes. | ||
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| For example, let's say that you are working with HTML and you want to create an enum class that contains some colors. |
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| For example, let's say that you are working with HTML and you want to create an enum class that contains some colors. | |
| For example, let's say you're working with HTML and want to create an enum class containing some colors. |
| In this example, the `containsRed()` member function accesses the value of the enum constant's `rgb` property using the | ||
| `this` keyword, and checks if the hexadecimal value contains `FF` as its first bits to return a boolean value. | ||
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| For more information about enum classes, see [Enum classes](enum-classes.md). |
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| For more information about enum classes, see [Enum classes](enum-classes.md). | |
| For more information, see [Enum classes](enum-classes.md). |
| ``` | ||
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| In this example, the `containsRed()` member function accesses the value of the enum constant's `rgb` property using the | ||
| `this` keyword, and checks if the hexadecimal value contains `FF` as its first bits to return a boolean value. |
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| `this` keyword, and checks if the hexadecimal value contains `FF` as its first bits to return a boolean value. | |
| `this` keyword and checks if the hexadecimal value contains `FF` as its first bits to return a boolean value. |
| ### Inline value classes | ||
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| Sometimes in your code, you may want to create small objects from classes and use them only briefly. This approach can | ||
| have a performance impact. Inline value classes are a special type of class that avoid this performance impact. However, |
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| have a performance impact. Inline value classes are a special type of class that avoid this performance impact. However, | |
| have a performance impact. Inline value classes are a special type of class that avoids this performance impact. However, |
| * Creates an instance of the `Email` class called `email`. | ||
| * Calls the `sendEmail()` function on the `email` object. | ||
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| By using an inline value class, the class is inlined and used directly in your code without creating an object. This can |
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| By using an inline value class, the class is inlined and used directly in your code without creating an object. This can | |
| By using an inline value class, you make the class inlined and can use it directly in your code without creating an object. This can |
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This PR is to add the second chapter of the intermediate tour to the staging branch.