feat: introduced withAdapterItem<SomeItem> { } to replace error prone and cumbersome (getAdapterItem() as? SomeItem)?.apply { }

Author: gotev

README.md

@@ -394,13 +394,13 @@ open class ExampleItem(private val context: Context, private val text: String)
 
         init {
             titleField.setOnClickListener {
-                (getAdapterItem() as? ExampleItem)?.apply {
+                withAdapterItem<ExampleItem> {
                     onTitleClicked(adapterPosition)
                 }
             }
 
             subtitleField.setOnClickListener {
-                (getAdapterItem() as? ExampleItem)?.apply {
+                withAdapterItem<ExampleItem> {
                     onSubTitleClicked(adapterPosition)
                 }
             }
@@ -412,15 +412,15 @@ open class ExampleItem(private val context: Context, private val text: String)
 As you can see, to handle click events on a view, you have to create a click listener in the ViewHolder and propagate an event to the `AdapterItem`:
 ```kotlin
 titleField.setOnClickListener {
-    (getAdapterItem() as? ExampleItem)?.apply {
+    withAdapterItem<ExampleItem> {
         onTitleClicked(adapterPosition)
     }
 }
 ```
 You can call any method defined in your `AdapterItem` and pass whatever parameters you want. It's important that you honor nullability, as each ViewHolder has a weak reference to its `AdapterItem`, so to prevent crashes at runtime always use the form:
 
 ```kotlin
-(getAdapterItem() as? YourAdapterItem)?.apply {
+withAdapterItem<ExampleItem> {
     // methods to call on the adapter item
 }
 ```
@@ -482,7 +482,7 @@ class TextWithButtonItem(private val text: String) : AdapterItem<TextWithButtonI
 
         init {
             buttonField.setOnClickListener {
-                (getAdapterItem() as? TextWithButtonItem)?.apply {
+                withAdapterItem<TextWithButtonItem> {
                     pressed = buttonField.isChecked
                     notifyItemChanged()
                 }
@@ -496,7 +496,7 @@ In the `Holder` we have added a click listener to the `ToggleButton`. When the u
 So, to recap, the <a name="eventLifecycle"></a>event lifecycle is:
 ```kotlin
 // gets ViewHolder's AdapterItem
-(getAdapterItem() as? YourAdapterItem)?.apply {
+withAdapterItem<YourAdapterItem> {
     // methods to call on the adapter item
 
     // (optional)

app/demo/src/main/java/net/gotev/recycleradapterdemo/adapteritems/SelectableItem.kt

@@ -28,7 +28,7 @@ open class SelectableItem(val label: String, val onClick: ((item: SelectableItem
 
         init {
             toggleField.setOnClickListener {
-                (getAdapterItem() as? SelectableItem)?.apply {
+                withAdapterItem<SelectableItem> {
                     selected = !selected
                     onClick?.invoke(this)
                 }

app/demo/src/main/java/net/gotev/recycleradapterdemo/adapteritems/TextWithToggleItem.kt

@@ -27,7 +27,7 @@ class TextWithToggleItem(private val text: String) : AdapterItem<TextWithToggleI
 
         init {
             itemView.setOnClickListener {
-                (getAdapterItem() as? TextWithToggleItem)?.apply {
+                withAdapterItem<TextWithToggleItem> {
                     pressed = !buttonField.isChecked
                     notifyItemChanged()
                 }

app/demo/src/main/java/net/gotev/recycleradapterdemo/adapteritems/TitleSubtitleItem.kt

@@ -39,13 +39,13 @@ open class TitleSubtitleItem(private val title: String, private val subtitle: St
 
         init {
             titleField.setOnClickListener {
-                (getAdapterItem() as? TitleSubtitleItem)?.apply {
+                withAdapterItem<TitleSubtitleItem> {
                     onTitleClicked(itemView.context, adapterPosition)
                 }
             }
 
             subtitleField.setOnClickListener {
-                (getAdapterItem() as? TitleSubtitleItem)?.apply {
+                withAdapterItem<TitleSubtitleItem> {
                     onSubTitleClicked(itemView.context, adapterPosition)
                 }
             }

recycleradapter/src/main/java/net/gotev/recycleradapter/RecyclerAdapterViewHolder.kt

@@ -16,8 +16,17 @@ abstract class RecyclerAdapterViewHolder(itemView: View) : RecyclerView.ViewHold
         adapter = WeakReference(recyclerAdapter)
     }
 
+    @Deprecated(
+        message = "use withAdapterItem<Type> { } instead",
+        level = DeprecationLevel.WARNING
+    )
     protected fun getAdapterItem() = adapter?.get()?.getAdapterItem(this)
 
+    @Suppress("UNCHECKED_CAST")
+    protected fun <T: AdapterItem<*>> withAdapterItem(action: T.() -> Unit) {
+        (adapter?.get()?.getAdapterItem(this) as? T)?.apply(action)
+    }
+
     /**
      * Notifies that the model associated to this ViewHolder has been changed.
      */