Intermediate tour: Properties chapter #4608

sarahhaggarty · 2024-12-11T11:07:59Z

This PR is to add the third chapter of the intermediate tour to the staging branch.

# Conflicts: # docs/kr.tree

danil-pavlov · 2024-12-17T17:44:32Z

docs/topics/tour/kotlin-tour-intermediate-properties.md

+## Backing fields
+
+In Kotlin, properties have default `get()` and `set()` functions, known as property accessors, which handle retrieving 
+and modifying their values. While these default functions are not explicitly visible in the code, they are automatically


While these default functions are not explicitly visible in the code, the compiler automatically generates them to manage

danil-pavlov · 2024-12-17T17:49:41Z

docs/topics/tour/kotlin-tour-intermediate-properties.md

+
+Just like extension functions, there are also extension properties. Extension properties allow you to add new properties
+to existing classes without modifying their source code. However, extension properties in Kotlin do **not** have backing
+fields. This means that Kotlin doesn't provide default `get()` and `set()` functions automatically. You have to write them


For me it seems like 3 sentences here are about the same idea, maybe shorten it a little bit?

However, extension properties in Kotlin do not have backing fields. This means you need to declare get() and set() functions yourself.

danil-pavlov · 2024-12-17T17:51:01Z

docs/topics/tour/kotlin-tour-intermediate-properties.md

+{validate="false"}
+
+Extension properties are most useful when you want a property to contain a computed value without using inheritance.
+You can think of extension properties working like a function that has only a single parameter: the receiver object.


Suggested change

You can think of extension properties working like a function that has only a single parameter: the receiver object.

You can think of extension properties working like a function with only one parameter: the receiver object.

danil-pavlov · 2024-12-17T17:51:40Z

docs/topics/tour/kotlin-tour-intermediate-properties.md

+Extension properties are most useful when you want a property to contain a computed value without using inheritance.
+You can think of extension properties working like a function that has only a single parameter: the receiver object.
+
+For example, let's say that you have a data class called `Person` that has two properties: `firstName`, `lastName`.


Suggested change

For example, let's say that you have a data class called `Person` that has two properties: `firstName`, `lastName`.

For example, let's say that you have a data class called `Person` with two properties: `firstName` and `lastName`.

danil-pavlov · 2024-12-17T17:57:07Z

docs/topics/tour/kotlin-tour-intermediate-properties.md

+In these functions:
+
+* The `operator` keyword marks these functions as operator functions, enabling them to overload the `get()` and `set()` functions.
+* The `thisRef` parameter refers to the object **containing** the delegated property. By default, the type is set to `Any?` but you may need to declare a more specific type.


Suggested change

* The `thisRef` parameter refers to the object **containing** the delegated property. By default, the type is set to `Any?` but you may need to declare a more specific type.

* The `thisRef` parameter refers to the object **containing** the delegated property. By default, the type is set to `Any?`, but you may need to declare a more specific type.

danil-pavlov · 2024-12-17T18:36:25Z

docs/topics/tour/kotlin-tour-intermediate-properties.md

+
+<deflist collapsible="true">
+    <def title="Hint 2">
+        You can use the <a href="https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/build-list.html"><code>buildList()</code></a> function to create and manage a list, instead of manually creating and returning a mutable list. The <code>buildList()</code> function uses a lambda with a receiver, which you learned about in earlier chapters.


Suggested change

You can use the <a href="https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/build-list.html"><code>buildList()</code></a> function to create and manage a list, instead of manually creating and returning a mutable list. The <code>buildList()</code> function uses a lambda with a receiver, which you learned about in earlier chapters.

You can use the <a href="https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/build-list.html"><code>buildList()</code></a> function to create and manage a list instead of manually creating and returning a mutable list. The <code>buildList()</code> function uses a lambda with a receiver, which you learned about in earlier chapters.

danil-pavlov · 2024-12-17T18:38:21Z

docs/topics/tour/kotlin-tour-intermediate-properties.md

+them whenever it goes below a certain threshold. You have a `Budget` class that is initialized with a `totalBudget` property
+that contains the initial budget amount. Within the class, create an observable property called `remainingBudget` that prints:
+
+* A warning when it is set to lower than 20% of the initial budget.


Suggested change

* A warning when it is set to lower than 20% of the initial budget.

* A warning when the value is lower than 20% of the initial budget.

danil-pavlov · 2024-12-17T18:40:31Z

docs/topics/tour/kotlin-tour-intermediate-properties.md

+that contains the initial budget amount. Within the class, create an observable property called `remainingBudget` that prints:
+
+* A warning when it is set to lower than 20% of the initial budget.
+* A good news message when the budget is increased from the previous value.


Suggested change

* A good news message when the budget is increased from the previous value.

* An encouraging message when the budget is increased from the previous value.

danil-pavlov · 2024-12-17T18:46:14Z

docs/topics/tour/kotlin-tour-intermediate-properties.md

+* The `get()` function retrieves the property value from the field: `""`.
+* The `set()` function accepts `value` as a parameter and assigns it to the field, where `value` is `""`. 
+
+Access to the backing field is useful when you want to perform additional logic in your `get()` or `set()` functions 


Suggested change

Access to the backing field is useful when you want to perform additional logic in your `get()` or `set()` functions

Access to the backing field is useful when you want to add extra logic in your `get()` or `set()` functions

danil-pavlov · 2024-12-17T18:49:03Z

docs/topics/tour/kotlin-tour-intermediate-properties.md

+{style="note"}
+
+Just like with extension functions, we use extension properties widely in the Kotlin standard library. For example,
+consider the [`lastIndex` property](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.text/last-index.html) for a `CharSequence`.


Suggested change

consider the [`lastIndex` property](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.text/last-index.html) for a `CharSequence`.

see the [`lastIndex` property](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.text/last-index.html) for a `CharSequence`.

sarahhaggarty requested a review from a team as a code owner December 11, 2024 11:08

sarahhaggarty force-pushed the intermediate-tour-properties branch from 097b3cd to 91524c4 Compare December 11, 2024 11:09

danil-pavlov self-assigned this Dec 11, 2024

add intermediate properties chapter

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sarahhaggarty force-pushed the intermediate-tour-properties branch from 91524c4 to 8dffea5 Compare December 11, 2024 16:00

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Intermediate tour: Properties chapter #4608

Intermediate tour: Properties chapter #4608

sarahhaggarty commented Dec 11, 2024

danil-pavlov Dec 17, 2024

danil-pavlov Dec 17, 2024

danil-pavlov Dec 17, 2024

danil-pavlov Dec 17, 2024

danil-pavlov Dec 17, 2024

danil-pavlov Dec 17, 2024

danil-pavlov Dec 17, 2024

danil-pavlov Dec 17, 2024

danil-pavlov Dec 17, 2024

danil-pavlov Dec 17, 2024

	You can think of extension properties working like a function that has only a single parameter: the receiver object.
	You can think of extension properties working like a function with only one parameter: the receiver object.

	For example, let's say that you have a data class called `Person` that has two properties: `firstName`, `lastName`.
	For example, let's say that you have a data class called `Person` with two properties: `firstName` and `lastName`.

	* The `thisRef` parameter refers to the object containing the delegated property. By default, the type is set to `Any?` but you may need to declare a more specific type.
	* The `thisRef` parameter refers to the object containing the delegated property. By default, the type is set to `Any?`, but you may need to declare a more specific type.

	You can use the <a href="https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/build-list.html"><code>buildList()</code></a> function to create and manage a list, instead of manually creating and returning a mutable list. The <code>buildList()</code> function uses a lambda with a receiver, which you learned about in earlier chapters.
	You can use the <a href="https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/build-list.html"><code>buildList()</code></a> function to create and manage a list instead of manually creating and returning a mutable list. The <code>buildList()</code> function uses a lambda with a receiver, which you learned about in earlier chapters.

	* A warning when it is set to lower than 20% of the initial budget.
	* A warning when the value is lower than 20% of the initial budget.

	* A good news message when the budget is increased from the previous value.
	* An encouraging message when the budget is increased from the previous value.

	Access to the backing field is useful when you want to perform additional logic in your `get()` or `set()` functions
	Access to the backing field is useful when you want to add extra logic in your `get()` or `set()` functions

	consider the [`lastIndex` property](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.text/last-index.html) for a `CharSequence`.
	see the [`lastIndex` property](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.text/last-index.html) for a `CharSequence`.

Intermediate tour: Properties chapter #4608

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