From 107d03f6ef1bb6ffecca528b02985a1aa41cd719 Mon Sep 17 00:00:00 2001
From: Ichthyostega <prg@ichthyostega.de>
Date: Sun, 29 Dec 2024 23:55:19 +0100
Subject: [PATCH] Invocation: invoke the param-functors and build extension
 block

Relying basically on the trick to invoke std::apply with a generic variadic Lambda
onto the tuple of functors; within the lambda we can use variadic expansion
to pass the results directly into the builder and so construct the param-tuple in-place.


Oh well.
2024 is almost gone by now.
Had to endure yet another performance of Beethoven's 9th symphony...
---
 src/steam/engine/param-weaving-pattern.hpp |  8 ++++---
 tests/core/steam/engine/node-feed-test.cpp |  3 +++
 wiki/thinkPad.ichthyo.mm                   | 26 ++++++++++++++++++----
 3 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/src/steam/engine/param-weaving-pattern.hpp b/src/steam/engine/param-weaving-pattern.hpp
index a4d97b00f..5341d37e8 100644
--- a/src/steam/engine/param-weaving-pattern.hpp
+++ b/src/steam/engine/param-weaving-pattern.hpp
@@ -113,9 +113,11 @@ namespace engine {
       typename ChainCons::NewFrame
       buildParamDataBlock (TurnoutSystem& turnoutSys)
         {
-          auto invoke = [&](auto& fun) { return fun(turnoutSys); };
-          ParamTup params = lib::meta::mapEach(functors_, invoke);
-          //////////////////////////////////////////////////////////////OOO now need to extract them
+          return std::apply ([&](auto&&... paramFun)
+                                  {  //    invoke parameter-functors and build NewFrame from results
+                                    return ChainCons::build (paramFun (turnoutSys) ...);
+                                  }
+                            ,functors_);
         }
       
       
diff --git a/tests/core/steam/engine/node-feed-test.cpp b/tests/core/steam/engine/node-feed-test.cpp
index 6ef694440..0c964c1f2 100644
--- a/tests/core/steam/engine/node-feed-test.cpp
+++ b/tests/core/steam/engine/node-feed-test.cpp
@@ -131,6 +131,9 @@ SHOW_EXPR(v0)
 SHOW_EXPR(v1)
 
           auto paramBlock = spec.buildParamDataBlock (turnoutSys);
+SHOW_EXPR(paramBlock)
+SHOW_EXPR(paramBlock.get<0>())
+SHOW_EXPR(paramBlock.get<1>())
           
           TODO ("implement a simple Builder for ParamAgent-Node");
           TODO ("then use both together to demonstrate a param data feed here");
diff --git a/wiki/thinkPad.ichthyo.mm b/wiki/thinkPad.ichthyo.mm
index b5a9ba876..bc9c9745a 100644
--- a/wiki/thinkPad.ichthyo.mm
+++ b/wiki/thinkPad.ichthyo.mm
@@ -94325,13 +94325,31 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 </node>
 </node>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1735438743590" ID="ID_973914193" MODIFIED="1735438756220" TEXT="Storage-Tupel erzeugen">
-<icon BUILTIN="flag-yellow"/>
-<node BACKGROUND_COLOR="#f8f1cb" COLOR="#a50125" CREATED="1735492888686" ID="ID_810676585" MODIFIED="1735492933273" TEXT="Problem: Storage-Block is non-copyable">
+<node COLOR="#338800" CREATED="1735438743590" ID="ID_973914193" MODIFIED="1735512420087" TEXT="Storage-Tupel erzeugen">
+<icon BUILTIN="button_ok"/>
+<node COLOR="#435e98" CREATED="1735492888686" ID="ID_810676585" MODIFIED="1735512377642" TEXT="Problem: Storage-Block is non-copyable">
 <icon BUILTIN="messagebox_warning"/>
+<node CREATED="1735512018597" ID="ID_1684262838" MODIFIED="1735512083855" TEXT="Konsequenz: k&#xf6;nnen ihn nicht aus dem Builder in das Turnout-System linken"/>
+<node CREATED="1735512085990" ID="ID_1280269467" MODIFIED="1735512398065" TEXT="das war aber so zu erwarten (und ich habe das auch akzeptiert)"/>
+<node CREATED="1735512107979" ID="ID_824666743" MODIFIED="1735512122317" TEXT="ohnehin passiert dieser Schritt im ParamWeavingPattern"/>
 </node>
-<node BACKGROUND_COLOR="#f8f1cb" COLOR="#a50125" CREATED="1735492909340" ID="ID_1181823322" MODIFIED="1735492933273" TEXT="erzeugen / bef&#xfc;llen ist auch tricky">
+<node COLOR="#435e98" CREATED="1735492909340" ID="ID_1181823322" MODIFIED="1735512377642" TEXT="erzeugen / bef&#xfc;llen ist auch tricky">
 <icon BUILTIN="messagebox_warning"/>
+<node CREATED="1735512137910" ID="ID_1638187110" MODIFIED="1735512154561" TEXT="deshalb gibt es aber auch diese Cons::build(elms...)-Funktion"/>
+<node CREATED="1735512156404" ID="ID_1834538695" MODIFIED="1735512274921" TEXT="L&#xf6;sung: die tuple-Apply-Technik direkt anwenden">
+<richcontent TYPE="NOTE"><html>
+  <head/>
+  <body>
+    <p>
+      also den gleichen Kniff, auf dem auch lib::meta::forEach und lib::meta::mapEach beruhen: man wendet per std::apply ein generisches variadisches Lambda auf die Tupel-Elemente an
+    </p>
+  </body>
+</html></richcontent>
+</node>
+<node CREATED="1735512277618" ID="ID_207555501" MODIFIED="1735512290335" TEXT="spezieller Twist: hier liegen die Param-Funktoren im Tupel"/>
+</node>
+<node COLOR="#338800" CREATED="1735512457951" ID="ID_895202142" MODIFIED="1735512478967" TEXT="im Test best&#xe4;tigt: funktioniert &#x263b;">
+<icon BUILTIN="button_ok"/>
 </node>
 </node>
 </node>