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lazybones

★ 353 Open GitHub ↗

😴 A lazy and fluent syntactic sugar for observing Activity, Fragment, and ViewModel lifecycles with lifecycle-aware properties.

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# Lazybones

😴 A lazy and fluent syntactic sugar for Android and ViewModel Lifecycle properties. 
Lazybones allows you to track and observe Activity, Fragment, and ViewModel lifecycles on lifecycle-aware properties.

> Ah... I'm a super lazy person. I just want to declare initialization and disposition together.

## Including in your project

[![Maven Central](https://img.shields.io/maven-central/v/com.github.skydoves/lazybones.svg?label=Maven%20Central)](https://search.maven.org/search?q=g:%22com.github.skydoves%22%20AND%20a:%22lazybones%22)

### Gradle 
Add the codes below to your **root** `build.gradle` file (not your module build.gradle file).
```gradle
allprojects {
    repositories {
        mavenCentral()
    }
}
```

Next, add the dependency below to your **module**'s `build.gradle` file.

```gradle
dependencies {
 implementation "com.github.skydoves:lazybones:1.0.4"
}
```
## SNAPSHOT 
[![Lazybones](https://img.shields.io/static/v1?label=snapshot&message=lazybones&logo=apache%20maven&color=C71A36)](https://oss.sonatype.org/content/repositories/snapshots/com/github/skydoves/lazybones/) 
Snapshots of the current development version of Lazybones are available, which track [the latest versions](https://oss.sonatype.org/content/repositories/snapshots/com/github/skydoves/lazybones/).

```gradle
repositories {
   maven { url 'https://oss.sonatype.org/content/repositories/snapshots/' }
}
```

# Usage

Lazybones provides `lifecycleAware` extension functions over the `LifecycleOwner`, which allows you to track and observe lifecycle changes on the same changing scope. Therefore, Lazybones can prevent function fragmentation as the lifecycle changes.

## lifecycleAware
You can initialize a lifecycle-aware object with the `lifecycleAware` extension. The `lifecycleAware` can be used to register/unregister listeners, initailize/clear, show/dismiss, and dispose objects following the lifecycle changes of the `lifecycleOwner`. With the `by` keyword and `lazy()` methhod, you can initialize an object lazily as the following example:

```kotlin
val myDialog: Dialog by lifecycleAware { getDarkThemeDialog(baseContext) }
    .onCreate { this.show() } // show the dialog when the lifecycle's state is onCreate.
    .onDestroy { this.dismiss() } // dismiss the dialog when the lifecycle's state is onDestroy.
    .lazy() // initlize the dialog lazily.
```

In the `onCreate` and `onDestroy` lambda scope, you can omit the `this` keyword. As you can see the following example, the `MediaPlayer` will be initialized and the `start()` will be executed on the `onCreate` state of the lifecycle. The `pause()`, `stop()`, and `release()` methods will be executed along the next lifecycle state.

```kotlin
private val mediaPlayer: MediaPlayer by lifecycleAware {
    MediaPlayer.create(this, R.raw.bgm3)
}.onCreate {
    isLooping = true
    start()
}.onStop {
    pause()
}.onResume {
    start()
}.onDestroy {
    stop()
    release()
}.lazy() // initialize the instance lazily.
```

The code above works the same as the following codes:

```kotlin
private val mediaPlayer: MediaPlayer by lazy { MediaPlayer.create(this, R.raw.bgm3) }

override fun onCreate(savedInstanceState: Bundle?) {
  super.onCreate(savedInstanceState)
  mediaPlayer.isLooping = true
  mediaPlayer.start()
}

override fun onPause() {
  super.onPause()
  mediaPlayer.pause()
}

override fun onStop() {
  super.onStop()
  mediaPlayer.pause()
}

override fun onResume() {
  super.onResume()
  mediaPlayer.start()
}

override fun onDestroy() {
  super.onDestroy()
  mediaPlayer.stop()
  mediaPlayer.release()
}
```

### CompositeDisposable in RxJava2

You can utilize Lazybones with RxJava as the following example:

```kotlin
val compositeDisposable by lifecycleAware { CompositeDisposable() }
    .onDestroy { dispose() } // call the dispose() method when onDestroy this activity.
    .lazy() // initialize a CompositeDisposable lazily.
```

As the above example, you can initialize and dispose of `CompositeDisposable` on the same method chain of the `lifecycleAware` extension.

### LifecycleAware Extensions

We can execute lambda functions following lifecycle changes and here are lifecycle relevant methods for the `lifecycleAware` extension.

```kotlin
.onCreate { } // the lambda will be invoked when onCreate.
.onStart { } // the lambda will be invoked when onStart.
.onResume { } // the lambda will be invoked when onResume.
.onPause { } // the lambda will be invoked when onPause.
.onStop { } // the lambda will be invoked when onStop.
.onDestroy { }  // the lambda will be invoked when onDestroy.
.on(On.Create) { } // we can set the lifecycle state manually as an attribute.
```

### LifecycleAware in Normal Classes

The `lifecycleAware` is an extension of the `lifecycleOwner`, so you can use it on a `LifecycleOwner` instance as the following:

```kotlin
class SomeClass(lifecycleOwner: LifecycleOwner) {

private val compositeDisposable by lifecycleOwner.lifecycleAware { CompositeDisposable() }
    .onDestroy { it.dispose() }
    .lazy()

...
```

## LifecycleAwareProperty

You can also initialize the `lifecycleAware` property immediately with the following example:

```kotlin
private val lifecycleAwareProperty = lifecycleAware(CompositeDisposable())
    // observe lifecycle's state and call the dispose() method when onDestroy  
    .observeOnDestroy { dispose() }
```

The `CompositeDisposable` will be initialized immediately, and it will be disposed of on the `observeOnDestroy` scope. Also, you can access the value of the property via the `value` field.

```kotlin
lifecycleAwareProperty.value.add(disposable)
lifecycleAwareProperty.value.dispose()
```

You can observe the lifecycle changes with `observe_` methods.

```kotlin
class MainActivity : AppCompatActivity() {

private val lifecycleAwareProperty = lifecycleAware(DialogUtil.getDarkTheme())

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(binding.root)

lifecycleAwareProperty
      .observeOnCreate { show() }
      .observeOnDestroy { dismiss() }
      .observeOnAny { .. }
      .observeOn(On.CREATE) { .. }
```

You can initialize them with the Kotlin DSL way as the following:

```kotlin
private val lifecycleAwareProperty = lifecycleAware(getDarkThemeDialog())
    .observe {
      onCreate { show() }
      onResume { restart() }
      onDestroy { dismiss() }
    }

```

### LifecycleAware for normal classes

The `lifecycleAware` is an extension of the `lifecycleOwner`, so you can use it on the `LifecycleOwner` instance as the following:

```kotlin
class SomeClass(lifecycleOwner: LifecycleOwner) {

private val TAG = MainViewModel::class.java.simpleName
  private val lifecycleAwareProperty = lifecycleOwner.lifecycleAware(Rabbit())

init {
    this.lifecycleAwareProperty
      .observeOnCreate { Log.d(TAG, "OnCreate: $this") }
      .observeOnStart { Log.d(TAG, "OnStart: $this") }
      .observeOnResume { Log.d(TAG, "OnResume: $this") }
      .observeOnPause { Log.d(TAG, "OnPause: $this") }
      .observeOnStop { Log.d(TAG, "OnStop: $this") }
      .observeOnDestroy { Log.d(TAG, "OnDestroy: $this") }
      .observeOnAny { }
      .observeOn(On.CREATE) { }
  }
  ...
```

## Lazybones for ViewModel

![carbon](https://user-images.githubusercontent.com/24237865/151923496-547e6fab-0a67-42b4-94da-6b0a1ce9088a.png)

Lazybones supports `lifecycleAware` for Jetpack ViewModel to track and observe the lifecycle changes of the ViewModel. Basically `Lazybones-ViewModel` allows you to observe two lifecycle changes: **Initialize** and **Clear**.

### Gradle

Add the dependency below to your **module's** `build.gradle` file:

```gradle
dependencies {
    implementation "com.github.skydoves:lazybones-viewmodel:1.0.4"
}
```

### LifecycleAware on ViewModel

You can use the `lifecycleAwrare` extension function on your ViewModel and observe lifecycle changes as the following example:

```kotlin
class MyViewModel : ViewModel() {

private val lifecycleAwareCompositeDisposable = lifecycleAware { CompositeDisposable() }
    .onInitialize {
      Log.d(TAG, "ViewModel is initialized")
    }.onClear {
      Log.d(TAG, "ViewModel is cleared")
      dispose() // dispose CompositeDisposable when viewModel is getting cleared
    }
}
```

You can get the value of the `lifecycleAware` with `value()` method as the following:

```kotlin
val compositeDisposable = lifecycleAwareCompositeDisposable.value()
compositeDisposable.add(disposable)
```

The example above shows you to initialize `CompositeDisposable` and observe the ViewModel's lifecycle changes. The `CompositeDisposable` will be disposed when ViewModel will be cleared such as `onCleared` is called.

### Lazy LifecycleAware on ViewModel

You can initialize `lifecycleAware` lazyily with the `by` keyword and `lazy()` function as the following:

```kotlin
class MyViewModel : ViewModel() {

private val compositeDisposable: CompositeDisposable by lifecycleAware { CompositeDisposable() }
    .onInitialize {
      Log.d(TAG, "viewModel is initialized")
    }.onClear {
      Log.d(TAG, "viewModel is cleared")
      dispose() // dispose CompositeDisposable when viewModel is getting cleared
    }.lazy()
}
```

## LifecycleAwareProperty on ViewModel

You can also initialize the `lifecycleAware` property immediately and observe the lifecycle changes as the following example:

```kotlin
val lifecycleAwareDisposable = lifecycleAware(CompositeDisposable())

init {
  lifecycleAwareDisposable
    .observeOnInitialize {  }
    .observeOnClear {  }
    .observeOn(OnViewModel.CLEAR) { .. }
}
```

## Find this library useful? :heart:
Support it by joining __[stargazers](https://github.com/skydoves/Lazybones/stargazers)__ for this repository. :star: 
And __[follow](https://github.com/skydoves)__ me for my next creations! 🤩

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the L

lazybones

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