Add dynamic attributes

core/src/scalive/LiveView.scala

@@ -8,6 +8,10 @@ class LiveView[Model] private (
     val static: ArraySeq[String],
     val dynamic: ArraySeq[LiveDyn[Model]]
 ):
+  assert(
+    static.size == dynamic.size + 1,
+    s"Static size : ${static.size}, Dynamic size : ${dynamic.size}"
+  )
   def update(model: Model): Unit =
     dynamic.foreach(_.update(model))
 
@@ -70,6 +74,8 @@ object LiveView:
     val (attrs, children) = el.mods.partitionMap {
       case Mod.StaticAttr(attr, value) =>
         Left(List(Some(s""" ${attr.name}="$value"""")))
+      case Mod.DynAttr(attr, _) =>
+        Left(List(Some(s""" ${attr.name}=""""), None, Some('"'.toString)))
       case Mod.Tag(el)                 => Right(buildStaticFragments(el))
       case Mod.Text(text)              => Right(List(Some(text)))
       case Mod.DynText[Model](_)       => Right(List(None))
@@ -85,8 +91,10 @@ object LiveView:
       startsUpdated: Boolean = false
   ): Seq[LiveDyn[Model]] =
     val (attrs, children) = el.mods.partitionMap {
-      case Mod.StaticAttr(_, _) => Left(List.empty)
       case Mod.Text(_)          => Right(List.empty)
+      case Mod.StaticAttr(_, _) => Left(List.empty)
+      case Mod.DynAttr(_, value) =>
+        Right(List(LiveDyn.Value(value, model, startsUpdated)))
       case Mod.Tag(el) =>
         Right(buildDynamic(el, model, startsUpdated))
       case Mod.DynText[Model](dynText) =>

core/src/scalive/View.scala

@@ -26,6 +26,7 @@ object Dyn:
 
 enum Mod[T]:
   case StaticAttr(attr: HtmlAttr, value: String)
+  case DynAttr(attr: HtmlAttr, value: Dyn[T, String])
   case Tag(el: HtmlElement[T])
   case Text(text: String)
   case DynText(dynText: Dyn[T, String])
@@ -51,5 +52,7 @@ val li = HtmlTag("li")
 
 class HtmlAttr(val name: String):
   def :=[T](value: String): Mod.StaticAttr[T] = Mod.StaticAttr(this, value)
+  def :=[T](value: Dyn[T, String]): Mod.DynAttr[T] = Mod.DynAttr(this, value)
 
 val idAttr = HtmlAttr("id")
+val cls = HtmlAttr("class")

core/src/scalive/main.scala

@@ -58,17 +58,18 @@ def main =
 
   println("Remove all")
   lv.update(
-    MyModel(List.empty)
+    MyModel(List.empty, "text-lg")
   )
   println(lv.diff.toJsonPretty)
 
-final case class MyModel(elems: List[NestedModel])
+final case class MyModel(elems: List[NestedModel], cls: String = "text-xs")
 final case class NestedModel(name: String, age: Int)
 
 object TestView extends View[MyModel]:
   val root: HtmlElement[MyModel] =
     div(
       idAttr := "42",
+      cls := model(_.cls),
       ul(
         model.splitByIndex(_.elems)(elem =>
           li(

core/test/src/scalive/LiveViewSpec.scala

@@ -10,6 +10,7 @@ object LiveViewSpec extends TestSuite:
       title: String = "title value",
       bool: Boolean = false,
       nestedTitle: String = "nested title value",
+      cls: String = "text-sm",
       items: List[NestedModel] = List.empty
   )
   final case class NestedModel(name: String, age: Int)
@@ -79,6 +80,43 @@ object LiveViewSpec extends TestSuite:
       }
     }
 
+    test("Dynamic attribute") {
+      val lv =
+        LiveView(
+          new View[TestModel]:
+            val root: HtmlElement[TestModel] =
+              div(cls := model(_.cls))
+          ,
+          TestModel()
+        )
+      test("init") {
+        assertEqualsJson(
+          lv.fullDiff,
+          Json
+            .Obj(
+              "s" -> Json
+                .Arr(Json.Str("<div class=\""), Json.Str("\"></div>")),
+              "0" -> Json.Str("text-sm")
+            )
+        )
+      }
+      test("diff no update") {
+        assertEqualsJson(lv.diff, emptyDiff)
+      }
+      test("diff with update") {
+        lv.update(TestModel(cls = "text-md"))
+        assertEqualsJson(
+          lv.diff,
+          Json.Obj("0" -> Json.Str("text-md"))
+        )
+      }
+      test("diff with update and no change") {
+        lv.update(TestModel(cls = "text-md"))
+        lv.update(TestModel(cls = "text-md"))
+        assertEqualsJson(lv.diff, emptyDiff)
+      }
+    }
+
     test("when mod") {
       val lv =
         LiveView(