From 35ea547fd1f64a27723c248df68c4dc405e71472 Mon Sep 17 00:00:00 2001
From: Ichthyostega <prg@ichthyostega.de>
Date: Mon, 9 Apr 2018 02:19:54 +0200
Subject: [PATCH] ElementAccess: (WIP) another unsuccessful attempt

Problem is, we can not even compile the conversion in the "other branch".
Thus we need to find some way to pick the suitable branch at compile time.

Quite similar to the solution found for binding Rec<GenNode> onto a typed Tuple
---
 src/gui/model/element-access.hpp | 40 ++++++++++++++-------------
 wiki/thinkPad.ichthyo.mm         | 47 ++++++++++++++++++++++++++++++--
 2 files changed, 66 insertions(+), 21 deletions(-)

diff --git a/src/gui/model/element-access.hpp b/src/gui/model/element-access.hpp
index cfddbefdf..648341d97 100644
--- a/src/gui/model/element-access.hpp
+++ b/src/gui/model/element-access.hpp
@@ -56,6 +56,7 @@
 #include "lib/nocopy.hpp"
 #include "lib/result.hpp"
 #include "include/limits.h"
+#include "lib/variant.hpp"
 #include "lib/access-casted.hpp"
 #include "gui/interact/ui-coord.hpp"
 //#include "lib/format-string.hpp"
@@ -73,6 +74,7 @@ namespace model {
   namespace error = lumiera::error;
   
   using interact::UICoord;
+  using lib::meta::Types;
 //  using util::isnil;
   using std::string;
   
@@ -105,16 +107,7 @@ namespace model {
       
       
     protected:
-      struct RawResult
-        {
-          model::Tangible* tangible = nullptr;
-          Gtk::Widget* gtkWidget    = nullptr;
-          
-          RawResult (model::Tangible& t) : tangible{&t} { }
-          RawResult (Gtk::Widget& w)     : gtkWidget{&w} { }
-          RawResult() =default;
-          // standard copy
-        };
+      using RawResult = lib::Variant<Types<model::Tangible*, Gtk::Widget*>>;
       
       /** @internal drill down according to coordinates, maybe create element */
       virtual RawResult performAccessTo (UICoord, size_t limitCreation)    =0;
@@ -138,14 +131,7 @@ namespace model {
   inline ElementAccess::Result<TAR&>
   ElementAccess::access (UICoord destination)
   {
-    RawResult targetElm = performAccessTo (destination, 0);
-    if (targetElm.tangible)
-      return util::AccessCasted<TAR&>::access (targetElm.tangible);
-    else
-    if (targetElm.gtkWidget)
-      return util::AccessCasted<TAR&>::access (targetElm.gtkWidget);
-    else
-      return "In current UI, there is no element at location "+string(destination);
+    return access_or_create<TAR> (destination, 0);
   }
   
   
@@ -159,7 +145,23 @@ namespace model {
   inline ElementAccess::Result<TAR&>
   ElementAccess::access_or_create (UICoord destination, size_t limitCreation)
   {
-    UNIMPLEMENTED ("delegate to a suitable polymorphic navigation/creation function");
+    struct TypeConverter
+      : RawResult::Visitor
+      {
+        Result<TAR&> result;
+        
+        void accept (model::Tangible* t) { result = util::AccessCasted<TAR&>::access (t); }
+        void accept (Gtk::Widget* w)     { result = util::AccessCasted<TAR&>::access (w); }
+      };
+///////////////////////////////////////////////////////////////////////////////////////////////////TODO Verdammter Mist!!!! es werden WIEDER beide Zweige compiliert, aber nur einer geht!!!      
+    RawResult targetElm = performAccessTo (destination, limitCreation);
+    if (targetElm.tangible)
+      return util::AccessCasted<TAR&>::access (targetElm.tangible);
+    else
+    if (targetElm.gtkWidget)
+      return util::AccessCasted<TAR&>::access (targetElm.gtkWidget);
+    else
+      return "In current UI, there is no element at location "+string(destination);
   }
   
   
diff --git a/wiki/thinkPad.ichthyo.mm b/wiki/thinkPad.ichthyo.mm
index 2fad10935..935d6abbb 100644
--- a/wiki/thinkPad.ichthyo.mm
+++ b/wiki/thinkPad.ichthyo.mm
@@ -12748,6 +12748,11 @@
 <icon BUILTIN="broken-line"/>
 </node>
 </node>
+<node CREATED="1523229374586" ID="ID_1962044591" MODIFIED="1523229381985" TEXT="sigc::trackable">
+<icon BUILTIN="button_cancel"/>
+<node CREATED="1523229383305" ID="ID_1786273483" MODIFIED="1523229392595" TEXT="hat kein RTTI"/>
+<node CREATED="1523229393567" ID="ID_1067337253" MODIFIED="1523229403706" TEXT="wohl bewu&#xdf;te Design-Entscheidung"/>
+</node>
 <node CREATED="1523228995279" ID="ID_924400738" MODIFIED="1523229065936" TEXT="mu&#xdf; mich wohl auf eine Menge von Basis-Typen festlegen">
 <icon BUILTIN="smily_bad"/>
 <node CREATED="1523229075403" ID="ID_808081590" MODIFIED="1523229080671" TEXT="model::Tangible"/>
@@ -12869,9 +12874,47 @@
 </node>
 <node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1523222380124" ID="ID_1101595897" MODIFIED="1523228027969" TEXT="mu&#xdf; pr&#xfc;fen, ob der Cast m&#xf6;glich ist">
 <icon BUILTIN="flag-yellow"/>
-<node CREATED="1523229139923" ID="ID_636796034" MODIFIED="1523229145773" TEXT="Variant?"/>
-<node CREATED="1523229147593" ID="ID_1510668106" MODIFIED="1523229166296" TEXT="if-else-Kaskade?">
+<node CREATED="1523229139923" ID="ID_636796034" MODIFIED="1523229481422" TEXT="Variant?">
 <icon BUILTIN="forward"/>
+<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1523229483619" ID="ID_1116388815" MODIFIED="1523232763524" TEXT="wohl einzige L&#xf6;sung?"/>
+<node BACKGROUND_COLOR="#fdfdcf" COLOR="#ff0000" CREATED="1523232748878" ID="ID_153055029" MODIFIED="1523232770707" TEXT="AUA --- geht auch nicht">
+<icon BUILTIN="broken-line"/>
+<node CREATED="1523232788680" ID="ID_849117954" MODIFIED="1523232797628" TEXT="&#xc4;ndert nix am Grundproblem">
+<icon BUILTIN="smily_bad"/>
+</node>
+<node CREATED="1523232798911" ID="ID_351873038" MODIFIED="1523232810481" TEXT="AccessCasted f&#xfc;r Zieltyp"/>
+<node CREATED="1523232811805" ID="ID_577095101" MODIFIED="1523232886443" TEXT="l&#xe4;&#xdf;t sich nur bei kompatiblem Basistyp &#xfc;berhaupt instantiieren">
+<icon BUILTIN="messagebox_warning"/>
+</node>
+<node CREATED="1523232888115" ID="ID_800807629" MODIFIED="1523232908023">
+<richcontent TYPE="NODE"><html>
+  <head>
+    
+  </head>
+  <body>
+    <p>
+      aber genau das ist hier jeweils nur <i>in einem Fall</i>&#160;gegeben
+    </p>
+  </body>
+</html>
+</richcontent>
+</node>
+<node CREATED="1523232932724" ID="ID_386898631" MODIFIED="1523232938983" TEXT="Runtime-Compiletime-Problem">
+<node CREATED="1523232945043" ID="ID_45452812" MODIFIED="1523232954053" TEXT="erst zur Laufzeit wissen wir, was zur&#xfc;ckkommt"/>
+<node CREATED="1523233007258" ID="ID_1076174983" MODIFIED="1523233019060" TEXT="aber zur Compilezeit m&#xfc;ssen wir schon den Cast vorbereiten"/>
+</node>
+<node CREATED="1523233031479" ID="ID_1135973571" MODIFIED="1523233048184" TEXT="Idee: Visitor spezialisieren">
+<node CREATED="1523233049316" ID="ID_278890079" MODIFIED="1523233057943" TEXT="er implementiert &#xfc;berhaupt nur den Fall, der geht"/>
+</node>
+</node>
+<node CREATED="1523229496001" ID="ID_190653452" MODIFIED="1523229516738" TEXT="bedeutet...">
+<icon BUILTIN="messagebox_warning"/>
+<node CREATED="1523229517523" ID="ID_1510464943" MODIFIED="1523229517523" TEXT="Variant-Visitor"/>
+<node CREATED="1523229519846" ID="ID_307916731" MODIFIED="1523229533208" TEXT="Einschr&#xe4;nkungen f&#xfc;r die Test-Dummies"/>
+</node>
+</node>
+<node CREATED="1523229147593" ID="ID_1510668106" MODIFIED="1523229476684" TEXT="if-else-Kaskade?">
+<icon BUILTIN="button_cancel"/>
 </node>
 </node>
 <node CREATED="1523225025493" ID="ID_1731501078" MODIFIED="1523225070764" TEXT="der interne Aufruf kann einen Pointer liefern">