Update some things.

Shared/Shared.h

@@ -75,12 +75,73 @@ public:
 
 class BaseSubsystem {
 public:
-    Engine<BaseSubsystem> * engine = nullptr;
     virtual void init() {}
     virtual void reload() {}
     virtual void deinit() {}
-    virtual void render() {}
-    virtual void tick() {}
 };
 
+template<typename T> requires std::integral<T> || std::floating_point<T>
+class Composed {
+    enum ModifierType {
+        Add, Multiply
+    };
+    using Modifier = std::pair<ModifierType, T>;
+    
+    uint64_t nextID = 0;
+    
+    std::vector<Modifier> modifiers;
+    T _value;
+public:
+    Composed() : Composed(T{0}) {}
+    Composed(T base) {
+        add(Add, base);
+    }
+    
+    T value() {
+        return _value;
+    }
+    
+    void recompute() {
+        T sum;
+        T fac;
+        for (auto [type, value] : modifiers) {
+            if (type == Add) {
+                sum += value;
+            } else if (type == Multiply) {
+                fac *= value;
+            }
+        }
+        
+        _value = sum * fac;
+    }
+    
+    uint64_t add(ModifierType type, T value) {
+        modifiers.emplace_back(type, value);
+        recompute();
+        return nextID++;
+    }
+    
+    bool remove(uint64_t id) {
+        auto it = std::find_if(modifiers.begin(), modifiers.end(),
+                               [id](const Modifier & m) { return m.id == id; });
+        if (it == modifiers.end()) return false;
+
+        modifiers.erase(it);
+        recompute();
+        return true;
+    }
+
+    bool update(uint64_t id, T newValue) {
+        auto it = std::find_if(modifiers.begin(), modifiers.end(),
+                               [id](const Modifier& m) { return m.id == id; });
+        if (it == modifiers.end()) return false;
+
+        it->value = newValue;
+        recompute();
+        return true;
+    }
+};
+
+void log(std::string msg);
+
 }