Add operator setValue to StoryParameterDelegate to allow changing its state in Story code

Author: eymar

gallery-demo/src/commonMain/kotlin/storytale/gallery/demo/Simple inputs.story.kt

@@ -8,8 +8,6 @@ import androidx.compose.material3.Checkbox
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Switch
 import androidx.compose.material3.Text
-import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.remember
 import org.jetbrains.compose.storytale.story
 
 val Button by story {
@@ -29,11 +27,11 @@ val Button by story {
 }
 
 val Checkbox by story {
-    val checked = remember { mutableStateOf(false) }
-    Checkbox(checked.value, onCheckedChange = { checked.value = it })
+    var checked by parameter(false)
+    Checkbox(checked, onCheckedChange = { checked = it })
 }
 
 val Switch by story {
-    val checked = remember { mutableStateOf(false) }
-    Switch(checked.value, onCheckedChange = { checked.value = it })
+    var checked by parameter(false)
+    Switch(checked, onCheckedChange = { checked = it })
 }

modules/runtime-api/src/commonMain/kotlin/org/jetbrains/compose/storytale/Story.kt

@@ -13,6 +13,5 @@ data class Story(
     internal val nameToParameterMapping = linkedMapOf<String, StoryParameter<*>>() // using linkedMap to keep the order
     val parameters inline get() = nameToParameterMapping.values.toList()
 
-    @Composable
     inline fun <reified T> parameter(defaultValue: T) = StoryParameterDelegate(this, T::class, defaultValue)
 }

modules/runtime-api/src/commonMain/kotlin/org/jetbrains/compose/storytale/StoryParameter.kt

@@ -1,17 +1,16 @@
 package org.jetbrains.compose.storytale
 
-import androidx.compose.runtime.Composable
 import androidx.compose.runtime.MutableState
 import kotlin.reflect.KClass
 
 class StoryParameter<T>(
     val name: String,
     val type: KClass<*>,
-    private val initializeMutableState: @Composable () -> MutableState<T>,
+    private val initializeMutableState: () -> MutableState<T>,
 ) {
     private var _state: MutableState<T>? = null
     val state: MutableState<T>
-        @Composable get() {
+        get() {
             var state = _state
             if (state == null) {
                 state = initializeMutableState()

modules/runtime-api/src/commonMain/kotlin/org/jetbrains/compose/storytale/StoryParameterDelegate.kt

@@ -1,8 +1,7 @@
 package org.jetbrains.compose.storytale
 
-import androidx.compose.runtime.Composable
+import androidx.compose.runtime.MutableState
 import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.remember
 import kotlin.reflect.KClass
 import kotlin.reflect.KProperty
 
@@ -11,13 +10,17 @@ class StoryParameterDelegate<T>(
     private val type: KClass<*>,
     private val defaultValue: T,
 ) {
-    @Composable
+    @Suppress("UNCHECKED_CAST")
     operator fun getValue(thisRef: Any?, property: KProperty<*>): T = story.nameToParameterMapping.getValue(property.name).state.value as T
 
-    @Composable
+    @Suppress("UNCHECKED_CAST")
+    operator fun setValue(thisRef: Any?, property: KProperty<*>, value: T) {
+        (story.nameToParameterMapping.getValue(property.name).state as MutableState<T>).value = value
+    }
+
     operator fun provideDelegate(thisRef: Any?, property: KProperty<*>) = also {
         story.nameToParameterMapping.getOrPut(property.name) {
-            StoryParameter(property.name, type) { remember { mutableStateOf(defaultValue) } }
+            StoryParameter(property.name, type) { mutableStateOf(defaultValue) }
         }
     }
 }