From 9bd3e550dcbec2d1fd71bc851eaaefcba82ab5ef Mon Sep 17 00:00:00 2001
From: Ichthyostega <prg@ichthyostega.de>
Date: Sat, 18 Apr 2026 16:25:14 +0200
Subject: [PATCH] BufferProvider: improve configuration of thread-local
 dispatch

Since thread_local implies a static setup, we need a way how to
build a new service instance. Usually this would be a default construction,
yet there might be services with special init requirements.

Using an explicit template parameter for this setup configuration
allows to make the primary template parameter just the service itself,
which makes the default usage much clearer.
---
 src/lib/local-slice.hpp        | 21 +++++++++++------
 tests/lib/local-slice-test.cpp |  9 +-------
 wiki/thinkPad.ichthyo.mm       | 41 ++++++++++++++++++++++++++++++++++
 3 files changed, 56 insertions(+), 15 deletions(-)

diff --git a/src/lib/local-slice.hpp b/src/lib/local-slice.hpp
index 83855218d..22c8132af 100644
--- a/src/lib/local-slice.hpp
+++ b/src/lib/local-slice.hpp
@@ -41,22 +41,29 @@
 
 
 namespace lib {
+
+  /** Extension point for LocalSlice: Service initialisation */
+  template<class SRV>
+  struct LocalSlice_DefaultSetup
+    {
+      using Service = SRV;
+      static Service init() { return Service(); }
+    };
+  
   
   /**
    * Common access point to thread-local service instances.
-   * @tparam CONF static config / setup to initialise the service.
+   * @tparam CONF setup to initialise the service.
    */
-  template<class CONF>
-  class LocalSlice
+  template<class SRV, class CONF =LocalSlice_DefaultSetup<SRV>>
+  struct LocalSlice
     {
-      using Service = CONF::Service;
-      
-    public:
       LocalSlice()  = default;
-      
       // using default copy/assignment
       
       
+      using Service = CONF::Service;
+      
       /** service access */
       Service&
       operator*()  const
diff --git a/tests/lib/local-slice-test.cpp b/tests/lib/local-slice-test.cpp
index 86bda458a..36761565c 100644
--- a/tests/lib/local-slice-test.cpp
+++ b/tests/lib/local-slice-test.cpp
@@ -57,14 +57,7 @@ namespace test {
           }
       };
     
-    struct DummySetup
-      {
-        using Service = DummyBackend;
-        
-        static Service init() { return Service(); }
-      };
-    
-    using DummySlice = LocalSlice<DummySetup>;
+    using DummySlice = LocalSlice<DummyBackend>;
     
     
     /**
diff --git a/wiki/thinkPad.ichthyo.mm b/wiki/thinkPad.ichthyo.mm
index 2b4513227..b17a58fa2 100644
--- a/wiki/thinkPad.ichthyo.mm
+++ b/wiki/thinkPad.ichthyo.mm
@@ -144308,6 +144308,47 @@ StM_bind(Builder&lt;R1&gt; b1, Extension&lt;R1,R2&gt; extension)
 <node CREATED="1776474854867" ID="ID_1487038882" MODIFIED="1776474859837" TEXT="CONF">
 <node CREATED="1776474861216" ID="ID_399712480" MODIFIED="1776474870435" TEXT="typedef Service"/>
 <node CREATED="1776474871327" ID="ID_142831800" MODIFIED="1776474879674" TEXT="eine init-Funktion"/>
+<node COLOR="#338800" CREATED="1776518244557" ID="ID_69243918" MODIFIED="1776522105417" TEXT="Verbesserung : Setup f&#xfc;r Service-Typ">
+<icon BUILTIN="button_ok"/>
+<node CREATED="1776518286073" ID="ID_992160718" MODIFIED="1776518303060" TEXT="LocalSlice&lt;SRV&gt;"/>
+<node CREATED="1776518303809" ID="ID_1039989287" MODIFIED="1776518323133" TEXT="normalerweise gen&#xfc;gt ein default-Setup-Template"/>
+<node COLOR="#435e98" CREATED="1776518324108" ID="ID_1914807086" MODIFIED="1776522047530" TEXT="explizite Spezialisierung soll m&#xf6;glich sein">
+<icon BUILTIN="yes"/>
+<node CREATED="1776521876873" ID="ID_1636226712" MODIFIED="1776522039333" TEXT="puh ... das wird in jedem Fall h&#xe4;sslich">
+<richcontent TYPE="NOTE"><html>
+  <head>
+    
+  </head>
+  <body>
+    <p>
+      man mu&#223; den aktuellen Namespace schlie&#223;en, in lib gehen, dort die explizite Spezialisierung definieren...
+    </p>
+  </body>
+</html>
+</richcontent>
+<icon BUILTIN="smiley-angry"/>
+</node>
+<node CREATED="1776521934417" ID="ID_130169122" MODIFIED="1776522032176" TEXT="L&#xf6;sung: 2.Template-Parameter mit Default-Init">
+<icon BUILTIN="idea"/>
+</node>
+<node CREATED="1776521973780" ID="ID_1887344423" MODIFIED="1776522004871" TEXT="default ist dann LocalSlice_DefaultSetup&lt;SRV&gt;">
+<richcontent TYPE="NOTE"><html>
+  <head>
+    
+  </head>
+  <body>
+    <p>
+      direkt bei LocalSlice definiert; erzeugt eine default-konstruierte Instanz vom Service
+    </p>
+  </body>
+</html>
+</richcontent>
+</node>
+<node COLOR="#338800" CREATED="1776522006689" ID="ID_1991943573" MODIFIED="1776522019517" TEXT="getested: Spezialisierung ist m&#xf6;glich">
+<icon BUILTIN="button_ok"/>
+</node>
+</node>
+</node>
 </node>
 <node COLOR="#338800" CREATED="1776474884669" ID="ID_66962199" MODIFIED="1776477543983" TEXT="LocalSlice_test">
 <icon BUILTIN="button_ok"/>