added base methods for VNodeRef

experiments/refs/demo.nim

@@ -1,16 +1,30 @@
 include karaxprelude
 import future, sequtils
 
+type
+  CustomRef = ref object of VNodeRef
+
+method onAttach(r: CustomRef) =
+  kout(cstring"custom ref attached")
+
+method onDetach(r: CustomRef) =
+  kout(cstring"custom ref detached")
+
 var
   modelData = @[5, 2, 4]
 
   refA = VNodeRef()
   refB = VNodeRef()
+  refC = CustomRef()
   refSeq = newSeq[VNodeRef]()
 
 proc onClick(ev: Event, n: VNode) =
-  kout(refA.vnode)
-  kout(refB.vnode)
+  modelData.add(0)
+
+proc showRefs() =
+  kout(refA)
+  kout(refB)
+  kout(refC)
   kout(refSeq.map(nref => nref.vnode))
 
 proc secureRefSlot(i: int): VNodeRef =
@@ -24,10 +38,13 @@ proc view(): VNode =
       button(onclick=onClick):
         text "click me"
       # storing refs to single elements is straightforward now
-      tdiv(nref=refA):
-        text "A"
-      tdiv(nref=refB):
-        text "B"
+      if modelData.len mod 2 == 0:
+        tdiv(nref=refA):
+          text "A"
+        tdiv(nref=refB):
+          text "B"
+        tdiv(nref=refC):
+          text "C"
       # It's a bit more tricky when containers are involved:
       for i, x in modelData.pairs:
         tdiv(nref=secureRefSlot(i)):
@@ -36,4 +53,4 @@ proc view(): VNode =
 proc renderer(): VNode =
   view()
 
-setRenderer renderer
+setRenderer(renderer, showRefs)

src/karax.nim

@@ -68,10 +68,12 @@ proc wrapEvent(d: Node; n: VNode; k: EventKind; action: EventHandler) =
 template detach(n: VNode) =
   if not n.nref.isNil():
     n.nref.vnode = nil
+    n.nref.onDetach()
   n.dom = nil
 template attach(n: VNode) =
   if not n.nref.isNil():
     n.nref.vnode = n
+    n.nref.onAttach()
   n.dom = result
 
 proc vnodeToDom(n: VNode): Node =

src/vdom.nim

@@ -101,7 +101,7 @@ macro buildLookupTables(): untyped =
 buildLookupTables()
 
 type
-  VNodeRef* = ref object
+  VNodeRef* = ref object of RootObj
     vnode*: VNode
 
   EventHandler* = proc (ev: Event; target: VNode) {.closure.}
@@ -122,6 +122,10 @@ type
     dom*: Node ## the attached real DOM node. Can be 'nil' if the virtual node
                ## is not part of the virtual DOM anymore.
 
+method onAttach*(v: VNodeRef) {.base.} = discard
+method onDetach*(v: VNodeRef) {.base.} = discard
+method changed*(v: VNodeRef): bool {.base.} = false
+
 proc value*(n: VNode): cstring = n.text
 proc `value=`*(n: VNode; v: cstring) = n.text = v