Basic design for property builders

dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/MetaBuilder.kt

@@ -141,8 +141,15 @@ fun Meta.edit(builder: MetaBuilder.() -> Unit): MetaBuilder = builder().apply(bu
 /**
  * Build a [MetaBuilder] using given transformation
  */
+@Deprecated("To be replaced with fake constructor", ReplaceWith("Meta"))
 fun buildMeta(builder: MetaBuilder.() -> Unit): MetaBuilder = MetaBuilder().apply(builder)
 
+/**
+ * Build a [MetaBuilder] using given transformation
+ */
+@Suppress("FunctionName")
+fun Meta(builder: MetaBuilder.() -> Unit): MetaBuilder = MetaBuilder().apply(builder)
+
 /**
  * Build meta using given source meta as a base
  */

dataforge-meta/src/commonMain/kotlin/hep/dataforge/meta/transformations/MetaCaster.kt

@@ -0,0 +1,75 @@
+package hep.dataforge.meta.transformations
+
+import hep.dataforge.meta.Meta
+import hep.dataforge.meta.MetaItem
+import hep.dataforge.meta.get
+import hep.dataforge.meta.value
+import hep.dataforge.values.*
+
+/**
+ * A converter of generic object to and from [MetaItem]
+ */
+interface MetaCaster<T : Any> {
+    fun itemToObject(item: MetaItem<*>): T
+    fun objectToMetaItem(obj: T): MetaItem<*>
+
+    companion object {
+
+        val meta = object : MetaCaster<Meta> {
+            override fun itemToObject(item: MetaItem<*>): Meta = when (item) {
+                is MetaItem.NodeItem -> item.node
+                is MetaItem.ValueItem -> item.value.toMeta()
+            }
+
+            override fun objectToMetaItem(obj: Meta): MetaItem<*> = MetaItem.NodeItem(obj)
+        }
+
+        val value = object : MetaCaster<Value> {
+            override fun itemToObject(item: MetaItem<*>): Value = when (item) {
+                is MetaItem.NodeItem -> item.node[Meta.VALUE_KEY].value ?: error("Can't convert node to a value")
+                is MetaItem.ValueItem -> item.value
+            }
+
+            override fun objectToMetaItem(obj: Value): MetaItem<*> = MetaItem.ValueItem(obj)
+        }
+
+        val string = object : MetaCaster<String> {
+            override fun itemToObject(item: MetaItem<*>): String = when (item) {
+                is MetaItem.NodeItem -> item.node[Meta.VALUE_KEY].value ?: error("Can't convert node to a value")
+                is MetaItem.ValueItem -> item.value
+            }.string
+
+            override fun objectToMetaItem(obj: String): MetaItem<*> = MetaItem.ValueItem(obj.asValue())
+        }
+
+        val boolean = object : MetaCaster<Boolean> {
+            override fun itemToObject(item: MetaItem<*>): Boolean = when (item) {
+                is MetaItem.NodeItem -> item.node[Meta.VALUE_KEY].value ?: error("Can't convert node to a value")
+                is MetaItem.ValueItem -> item.value
+            }.boolean
+
+            override fun objectToMetaItem(obj: Boolean): MetaItem<*> = MetaItem.ValueItem(obj.asValue())
+        }
+
+        val double = object : MetaCaster<Double> {
+            override fun itemToObject(item: MetaItem<*>): Double = when (item) {
+                is MetaItem.NodeItem -> item.node[Meta.VALUE_KEY].value ?: error("Can't convert node to a value")
+                is MetaItem.ValueItem -> item.value
+            }.double
+
+            override fun objectToMetaItem(obj: Double): MetaItem<*> = MetaItem.ValueItem(obj.asValue())
+        }
+
+        val int = object : MetaCaster<Int> {
+            override fun itemToObject(item: MetaItem<*>): Int = when (item) {
+                is MetaItem.NodeItem -> item.node[Meta.VALUE_KEY].value ?: error("Can't convert node to a value")
+                is MetaItem.ValueItem -> item.value
+            }.int
+
+            override fun objectToMetaItem(obj: Int): MetaItem<*> = MetaItem.ValueItem(obj.asValue())
+        }
+    }
+}
+
+fun <T : Any> MetaCaster<T>.metaToObject(meta: Meta): T = itemToObject(MetaItem.NodeItem(meta))
+fun <T : Any> MetaCaster<T>.valueToObject(value: Value): T = itemToObject(MetaItem.ValueItem(value))

dataforge-meta/src/commonMain/kotlin/hep/dataforge/values/valueExtensions.kt

@@ -1,7 +1,6 @@
 package hep.dataforge.values
 
 import hep.dataforge.meta.Meta
-import hep.dataforge.meta.buildMeta
 
 /**
  * Check if value is null
@@ -35,4 +34,4 @@ val Value.doubleArray: DoubleArray
     }
 
 
-fun Value.toMeta() = buildMeta { Meta.VALUE_KEY put this }
+fun Value.toMeta() = Meta { Meta.VALUE_KEY put this }

dataforge-tables/src/commonMain/kotlin/hep/dataforge/tables/Table.kt

@@ -45,7 +45,7 @@ operator fun Collection<Column<*>>.get(name: String): Column<*>? = find { it.nam
 inline operator fun <C : Any, reified T : C> Table<C>.get(row: Int, column: String): T? =
     getValue(row, column, T::class)
 
-operator fun <C : Any, T : C> Table<C>.get(row: Int, column: Column<T>): T? = getValue(row, column.name, column.type)
+operator fun <C : Any, T : C> Table<C>.get(row: Int, column: ColumnHeader<T>): T? = getValue(row, column.name, column.type)
 
 interface Column<T : Any> : ColumnHeader<T> {
     val size: Int