Eliminates the useless type property from ViewEnvironmentKey.

samples/containers/android/src/main/java/com/squareup/sample/container/overviewdetail/OverviewDetailConfig.kt

@@ -31,7 +31,7 @@ enum class OverviewDetailConfig {
   Single;
 
   @OptIn(WorkflowUiExperimentalApi::class)
-  companion object : ViewEnvironmentKey<OverviewDetailConfig>(OverviewDetailConfig::class) {
+  companion object : ViewEnvironmentKey<OverviewDetailConfig>() {
     override val default = None
   }
 }

workflow-ui/compose-tooling/src/androidTest/java/com/squareup/workflow1/ui/compose/tooling/LegacyPreviewViewFactoryTest.kt

@@ -164,7 +164,7 @@ internal class LegacyPreviewViewFactoryTest {
     )
   }
 
-  object TestEnvironmentKey : ViewEnvironmentKey<String>(String::class) {
+  object TestEnvironmentKey : ViewEnvironmentKey<String>() {
     override val default: String get() = error("Not specified")
   }
 

workflow-ui/compose-tooling/src/androidTest/java/com/squareup/workflow1/ui/compose/tooling/PreviewViewFactoryTest.kt

@@ -194,7 +194,7 @@ internal class PreviewViewFactoryTest {
     )
   }
 
-  object TestEnvironmentKey : ViewEnvironmentKey<String>(String::class) {
+  object TestEnvironmentKey : ViewEnvironmentKey<String>() {
     override val default: String get() = error("Not specified")
   }
 

workflow-ui/compose/src/androidTest/java/com/squareup/workflow1/ui/compose/ComposeViewFactoryTest.kt

@@ -78,7 +78,7 @@ internal class ComposeViewFactoryTest {
   }
 
   @Test fun getsViewEnvironmentUpdates() {
-    val testEnvironmentKey = object : ViewEnvironmentKey<String>(String::class) {
+    val testEnvironmentKey = object : ViewEnvironmentKey<String>() {
       override val default: String get() = error("No default")
     }
 

workflow-ui/compose/src/androidTest/java/com/squareup/workflow1/ui/compose/LegacyComposeViewFactoryTest.kt

@@ -79,7 +79,7 @@ internal class LegacyComposeViewFactoryTest {
   }
 
   @Test fun getsViewEnvironmentUpdates() {
-    val testEnvironmentKey = object : ViewEnvironmentKey<String>(String::class) {
+    val testEnvironmentKey = object : ViewEnvironmentKey<String>() {
       override val default: String get() = error("No default")
     }
 

workflow-ui/core-android/src/androidTest/java/com/squareup/workflow1/ui/DecorativeViewFactoryTest.kt

@@ -30,7 +30,7 @@ internal class DecorativeViewFactoryTest {
       }
     }
 
-    val envString = object : ViewEnvironmentKey<String>(String::class) {
+    val envString = object : ViewEnvironmentKey<String>() {
       override val default: String get() = "Not set"
     }
 
@@ -120,7 +120,7 @@ internal class DecorativeViewFactoryTest {
       }
     }
 
-    val envString = object : ViewEnvironmentKey<String>(String::class) {
+    val envString = object : ViewEnvironmentKey<String>() {
       override val default: String get() = "Not set"
     }
 

workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/ScreenViewFactoryFinder.kt

@@ -85,9 +85,7 @@ public interface ScreenViewFactoryFinder {
       )
   }
 
-  public companion object : ViewEnvironmentKey<ScreenViewFactoryFinder>(
-    ScreenViewFactoryFinder::class
-  ) {
+  public companion object : ViewEnvironmentKey<ScreenViewFactoryFinder>() {
     override val default: ScreenViewFactoryFinder
       get() = object : ScreenViewFactoryFinder {}
   }

workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/container/AlertDialogThemeResId.kt

@@ -8,6 +8,6 @@ import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
  * for the `@StyleRes themeResId: Int` argument of `AlertDialog.Builder()`.
  */
 @WorkflowUiExperimentalApi
-public object AlertDialogThemeResId : ViewEnvironmentKey<Int>(type = Int::class) {
+public object AlertDialogThemeResId : ViewEnvironmentKey<Int>() {
   override val default: Int = 0
 }

workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/container/BackStackConfig.kt

@@ -29,7 +29,7 @@ public enum class BackStackConfig {
    */
   Other;
 
-  public companion object : ViewEnvironmentKey<BackStackConfig>(BackStackConfig::class) {
+  public companion object : ViewEnvironmentKey<BackStackConfig>() {
     override val default: BackStackConfig = None
   }
 }

workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/container/CoveredByModal.kt

@@ -12,6 +12,6 @@ import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
  * https://stackoverflow.com/questions/2886407/dealing-with-rapid-tapping-on-buttons
  */
 @WorkflowUiExperimentalApi
-internal object CoveredByModal : ViewEnvironmentKey<Boolean>(type = Boolean::class) {
+internal object CoveredByModal : ViewEnvironmentKey<Boolean>() {
   override val default: Boolean = false
 }

workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/container/DialogCollator.kt

@@ -254,7 +254,7 @@ internal class DialogCollator {
       ")"
   }
 
-  companion object : ViewEnvironmentKey<DialogCollator>(DialogCollator::class) {
+  companion object : ViewEnvironmentKey<DialogCollator>() {
     override val default: DialogCollator
       get() = error("Call ViewEnvironment.establishDialogCollator first.")
   }

workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/container/OverlayArea.kt

@@ -16,7 +16,7 @@ import kotlinx.coroutines.flow.StateFlow
 internal class OverlayArea(
   val bounds: StateFlow<Rect>
 ) {
-  companion object : ViewEnvironmentKey<OverlayArea>(type = OverlayArea::class) {
+  companion object : ViewEnvironmentKey<OverlayArea>() {
     override val default: OverlayArea = OverlayArea(MutableStateFlow(Rect()))
   }
 }

workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/container/OverlayDialogFactoryFinder.kt

@@ -36,9 +36,7 @@ public interface OverlayDialogFactoryFinder {
       )
   }
 
-  public companion object : ViewEnvironmentKey<OverlayDialogFactoryFinder>(
-    OverlayDialogFactoryFinder::class
-  ) {
+  public companion object : ViewEnvironmentKey<OverlayDialogFactoryFinder>() {
     override val default: OverlayDialogFactoryFinder = object : OverlayDialogFactoryFinder {}
   }
 }

workflow-ui/core-android/src/test/java/com/squareup/workflow1/ui/container/ScreenViewFactoryTestUtil.kt

@@ -32,7 +32,7 @@ internal fun mockView(): View {
   }
 }
 
-internal object SomeEnvValue : ViewEnvironmentKey<String>(String::class) {
+internal object SomeEnvValue : ViewEnvironmentKey<String>() {
   override val default: String get() = error("Unset")
 }
 

workflow-ui/core-common/api/core-common.api

@@ -99,12 +99,12 @@ public final class com/squareup/workflow1/ui/ViewEnvironment$Companion {
 }
 
 public abstract class com/squareup/workflow1/ui/ViewEnvironmentKey {
+	public fun <init> ()V
 	public fun <init> (Lkotlin/reflect/KClass;)V
 	public fun combine (Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
 	public final fun equals (Ljava/lang/Object;)Z
 	public abstract fun getDefault ()Ljava/lang/Object;
 	public final fun hashCode ()I
-	public final fun toString ()Ljava/lang/String;
 }
 
 public abstract interface class com/squareup/workflow1/ui/ViewRegistry {

workflow-ui/core-common/src/main/java/com/squareup/workflow1/ui/ViewEnvironment.kt

@@ -62,13 +62,22 @@ constructor(
 }
 
 /**
- * Defines a value that can be provided by a [ViewEnvironment] map, specifying its [type]
- * and [default] value.
+ * Defines a value that can be provided by a [ViewEnvironment] map, specifying its [default] value.
+ *
+ * It is hard to imagine a useful implementation of this that is not a Kotlin `object`.
+ * Preferred use is to have the `companion object` of [T] extend this class. See
+ * [BackStackConfig.Companion][com.squareup.workflow1.ui.container.BackStackConfig.Companion]
+ * for an example.
  */
 @WorkflowUiExperimentalApi
-public abstract class ViewEnvironmentKey<T : Any>(
-  private val type: KClass<T>
-) {
+public abstract class ViewEnvironmentKey<T : Any>() {
+  @Deprecated("Use no args constructor", ReplaceWith("ViewEnvironmentKey<T>()"))
+  public constructor(@Suppress("UNUSED_PARAMETER") type: KClass<T>) : this()
+
+  /**
+   * Defines the default value for this key. It is a grievous error for this value to be
+   * dynamic in any way.
+   */
   public abstract val default: T
 
   /**
@@ -80,15 +89,9 @@ public abstract class ViewEnvironmentKey<T : Any>(
     right: T
   ): T = right
 
-  final override fun equals(other: Any?): Boolean = when {
-    this === other -> true
-    other != null && this::class != other::class -> false
-    else -> type == (other as ViewEnvironmentKey<*>).type
+  final override fun equals(other: Any?): Boolean {
+    return this === other || (other != null && this::class == other::class)
   }
 
-  final override fun hashCode(): Int = type.hashCode()
-
-  final override fun toString(): String {
-    return "${this::class.simpleName}(${type.simpleName})"
-  }
+  final override fun hashCode(): Int = this::class.hashCode()
 }

workflow-ui/core-common/src/main/java/com/squareup/workflow1/ui/ViewRegistry.kt

@@ -81,7 +81,7 @@ public interface ViewRegistry {
     renderingType: KClass<out RenderingT>
   ): Entry<RenderingT>?
 
-  public companion object : ViewEnvironmentKey<ViewRegistry>(ViewRegistry::class) {
+  public companion object : ViewEnvironmentKey<ViewRegistry>() {
     override val default: ViewRegistry get() = ViewRegistry()
     override fun combine(
       left: ViewRegistry,

workflow-ui/core-common/src/test/java/com/squareup/workflow1/ui/ViewEnvironmentTest.kt

@@ -6,19 +6,19 @@ import org.junit.Test
 
 @OptIn(WorkflowUiExperimentalApi::class)
 internal class ViewEnvironmentTest {
-  private object StringHint : ViewEnvironmentKey<String>(String::class) {
+  private object StringHint : ViewEnvironmentKey<String>() {
     override val default = ""
   }
 
-  private object OtherStringHint : ViewEnvironmentKey<String>(String::class) {
+  private object OtherStringHint : ViewEnvironmentKey<String>() {
     override val default = ""
   }
 
   private data class DataHint(
     val int: Int = -1,
     val string: String = ""
   ) {
-    companion object : ViewEnvironmentKey<DataHint>(DataHint::class) {
+    companion object : ViewEnvironmentKey<DataHint>() {
       override val default = DataHint()
     }
   }
@@ -101,7 +101,7 @@ internal class ViewEnvironmentTest {
   }
 
   @Test fun `honors combine`() {
-    val combiningHint = object : ViewEnvironmentKey<String>(String::class) {
+    val combiningHint = object : ViewEnvironmentKey<String>() {
       override val default: String
         get() = error("")
 

workflow-ui/core-common/src/test/java/com/squareup/workflow1/ui/container/EnvironmentScreenTest.kt

@@ -19,7 +19,7 @@ internal class EnvironmentScreenTest {
   ) : ViewRegistry.Entry<T>
 
   private data class TestValue(val value: String) {
-    companion object : ViewEnvironmentKey<TestValue>(TestValue::class) {
+    companion object : ViewEnvironmentKey<TestValue>() {
       override val default: TestValue get() = error("Set a default")
     }
   }