Save system should work better now, just needed to switch to basic map. This would probably a lot better if tser.hpp supported std::any.

save.cpp

@@ -7,10 +7,10 @@ using namespace components;
 
 
 template<typename CompT>
-inline void extract(DinkyECS::World &world, std::vector<CompT> &into) {
+inline void extract(DinkyECS::World &world, std::map<DinkyECS::Entity, CompT> &into) {
   auto from_world = world.entity_map_for<CompT>();
   for(auto [entity, value] : from_world) {
-    into.push_back(std::any_cast<CompT>(value));
+    into[entity] = std::any_cast<CompT>(value);
   }
 }
 
@@ -18,7 +18,8 @@ void save::to_file(std::string path, DinkyECS::World &world) {
   SaveData save_data;
   tser::BinaryArchive archive;
 
-  save_data.player = world.get_the<Player>();
+  save_data.facts.player = world.get_the<Player>();
+
   extract<Position>(world, save_data.position);
   extract<Combat>(world, save_data.combat);
   extract<Motion>(world, save_data.motion);
@@ -31,6 +32,12 @@ void save::to_file(std::string path, DinkyECS::World &world) {
   out.flush();
 }
 
+template<typename CompT>
+inline void inject(DinkyECS::World &world, std::map<DinkyECS::Entity, CompT> &outof) {
+  for(auto [entity, value] : outof) {
+    world.set<CompT>(entity, value);
+  }
+}
 
 void save::from_file(std::string path, DinkyECS::World &world_out) {
   tser::BinaryArchive archive(0);
@@ -51,13 +58,8 @@ void save::from_file(std::string path, DinkyECS::World &world_out) {
   }
 
   auto save_data = archive.load<SaveData>();
-
-  // BUG: need the entities!
-  world_out.set_the<Player>(save_data.player);
-
-  for(auto position : save_data.position) {
-    auto entity = world_out.entity();
-    // BUG: actually do need the entities
-    world_out.set<Position>(entity, position);
-  }
+  world_out.set_the<Player>(save_data.facts.player);
+  inject<Position>(world_out, save_data.position);
+  inject<Combat>(world_out, save_data.combat);
+  inject<Motion>(world_out, save_data.motion);
 }

save.hpp

@@ -4,16 +4,24 @@
 #include "dinkyecs.hpp"
 #include "tser.hpp"
 #include <string>
-#include <vector>
+#include <map>
 
 namespace save {
-  struct SaveData {
+
+  struct Facts {
     components::Player player;
-    std::vector<components::Position> position;
-    std::vector<components::Motion> motion;
-    std::vector<components::Combat> combat;
 
-    DEFINE_SERIALIZABLE(SaveData, player, position, motion, combat);
+    DEFINE_SERIALIZABLE(Facts, player);
+  };
+
+  struct SaveData {
+    Facts facts;
+
+    std::map<DinkyECS::Entity, components::Position> position;
+    std::map<DinkyECS::Entity, components::Motion> motion;
+    std::map<DinkyECS::Entity, components::Combat> combat;
+
+    DEFINE_SERIALIZABLE(SaveData, facts, position, motion, combat);
   };
 
   void to_file(std::string path, DinkyECS::World &world);

tests/save.cpp

@@ -70,11 +70,15 @@ TEST_CASE("basic save a world", "[save]") {
 
   Position &position1 = world.get<Position>(player.entity);
   Position &position2 = in_world.get<Position>(player.entity);
-
-  // BUGGGGGGGG! This doesn't actually work, it's all fake
-  // The world uses an internal id to increment entities so
-  // by default player gets the first one, but all data after
-  // that is wrong.
   REQUIRE(position1.location.x == position2.location.x);
   REQUIRE(position1.location.y == position2.location.y);
+
+  Combat &combat1 = in_world.get<Combat>(player.entity);
+  Combat &combat2 = in_world.get<Combat>(player.entity);
+  REQUIRE(combat1.hp == combat2.hp);
+
+  Motion &motion1 = in_world.get<Motion>(player.entity);
+  Motion &motion2 = in_world.get<Motion>(player.entity);
+  REQUIRE(motion1.dx == motion2.dx);
+  REQUIRE(motion1.dy == motion2.dy);
 }