From 874a253292bfa01138b9938ec36bc06f13a8673e Mon Sep 17 00:00:00 2001
From: Alexander Nozik <altavir@gmail.com>
Date: Wed, 7 Apr 2021 15:34:27 +0300
Subject: [PATCH] Fix property usage for ObservableItemProvider

---
 build.gradle.kts                                   |  2 +-
 dataforge-meta/api/dataforge-meta.api              |  3 +--
 .../dataforge/meta/ObservableItemProvider.kt       | 14 ++++++++++++--
 .../space/kscience/dataforge/meta/SchemeTest.kt    |  4 +++-
 4 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/build.gradle.kts b/build.gradle.kts
index 741293ae..98a941bb 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -4,7 +4,7 @@ plugins {
 
 allprojects {
     group = "space.kscience"
-    version = "0.4.0-dev-6"
+    version = "0.4.0-dev-7"
 }
 
 subprojects {
diff --git a/dataforge-meta/api/dataforge-meta.api b/dataforge-meta/api/dataforge-meta.api
index ad2d9612..47b38de5 100644
--- a/dataforge-meta/api/dataforge-meta.api
+++ b/dataforge-meta/api/dataforge-meta.api
@@ -414,8 +414,7 @@ public abstract interface class space/kscience/dataforge/meta/ObservableItemProv
 }
 
 public final class space/kscience/dataforge/meta/ObservableItemProviderKt {
-	public static final fun onChange (Lspace/kscience/dataforge/meta/ObservableItemProvider;Lkotlin/reflect/KProperty1;Ljava/lang/Object;Lkotlin/jvm/functions/Function2;)V
-	public static synthetic fun onChange$default (Lspace/kscience/dataforge/meta/ObservableItemProvider;Lkotlin/reflect/KProperty1;Ljava/lang/Object;Lkotlin/jvm/functions/Function2;ILjava/lang/Object;)V
+	public static synthetic fun useProperty$default (Lspace/kscience/dataforge/meta/ObservableItemProvider;Lkotlin/reflect/KProperty1;Ljava/lang/Object;Lkotlin/jvm/functions/Function2;ILjava/lang/Object;)V
 }
 
 public abstract interface class space/kscience/dataforge/meta/ReadOnlySpecification {
diff --git a/dataforge-meta/src/commonMain/kotlin/space/kscience/dataforge/meta/ObservableItemProvider.kt b/dataforge-meta/src/commonMain/kotlin/space/kscience/dataforge/meta/ObservableItemProvider.kt
index 1a11441b..5d455d17 100644
--- a/dataforge-meta/src/commonMain/kotlin/space/kscience/dataforge/meta/ObservableItemProvider.kt
+++ b/dataforge-meta/src/commonMain/kotlin/space/kscience/dataforge/meta/ObservableItemProvider.kt
@@ -1,5 +1,6 @@
 package space.kscience.dataforge.meta
 
+import space.kscience.dataforge.misc.DFExperimental
 import space.kscience.dataforge.names.Name
 import space.kscience.dataforge.names.toName
 import kotlin.reflect.KProperty1
@@ -18,12 +19,21 @@ public interface ObservableItemProvider : ItemProvider {
 
 public interface ItemPropertyProvider: ObservableItemProvider, MutableItemProvider
 
-public fun <O : ObservableItemProvider, T : Any> O.onChange(
+/**
+ * Use the value of the property in a [callBack].
+ * The callback is called once immediately after subscription to pass the initial value.
+ *
+ * Optional [owner] property is used for
+ */
+@DFExperimental
+public fun <O : ObservableItemProvider, T : Any> O.useProperty(
     property: KProperty1<O, T?>,
     owner: Any? = null,
     callBack: O.(T?) -> Unit,
 ) {
-    onChange(null) { name, oldItem, newItem ->
+    //Pass initial value.
+    callBack(property.get(this))
+    onChange(owner) { name, oldItem, newItem ->
         if (name == property.name.toName() && oldItem != newItem) {
             callBack(property.get(this))
         }
diff --git a/dataforge-meta/src/commonTest/kotlin/space/kscience/dataforge/meta/SchemeTest.kt b/dataforge-meta/src/commonTest/kotlin/space/kscience/dataforge/meta/SchemeTest.kt
index d2407bb4..2b55658e 100644
--- a/dataforge-meta/src/commonTest/kotlin/space/kscience/dataforge/meta/SchemeTest.kt
+++ b/dataforge-meta/src/commonTest/kotlin/space/kscience/dataforge/meta/SchemeTest.kt
@@ -1,8 +1,10 @@
 package space.kscience.dataforge.meta
 
+import space.kscience.dataforge.misc.DFExperimental
 import kotlin.test.Test
 import kotlin.test.assertEquals
 
+@DFExperimental
 class SchemeTest {
     @Test
     fun testSchemeWrappingBeforeEdit(){
@@ -25,7 +27,7 @@ class SchemeTest {
     fun testSchemeSubscription(){
         val scheme = TestScheme.empty()
         var flag: Int? = null
-        scheme.onChange(TestScheme::a){a->
+        scheme.useProperty(TestScheme::a){a->
             flag = a
         }
         scheme.a = 2