Add factory example with scripted callbacks

CMakeLists.txt

@@ -259,6 +259,8 @@ if(BUILD_SAMPLES)
   target_link_libraries(memory_leak_test ${LIBS})
   add_executable(inheritance samples/inheritance.cpp)
   target_link_libraries(inheritance ${LIBS})
+  add_executable(factory samples/factory.cpp)
+  target_link_libraries(factory ${LIBS})
   add_executable(fun_call_performance samples/fun_call_performance.cpp)
   target_link_libraries(fun_call_performance ${LIBS})
 endif()

samples/factory.cpp

@@ -0,0 +1,103 @@
+#include <chaiscript/chaiscript.hpp>
+#include <chaiscript/chaiscript_stdlib.hpp>
+
+class Entity
+{
+  public:
+    int width;
+    int height;
+    int x;
+    int y;
+    std::string name;
+
+    std::function<void (Entity &)> updater;
+
+    Entity(const int t_width, const int t_height, const int t_x, const int t_y, std::string t_name)
+      : width(t_width), height(t_height), x(t_x), y(t_y), name(std::move(t_name))
+    {
+    }
+};
+
+class Factory
+{
+  public:
+    // we may as well pass the parameters for the entity to the factory method, this does the initialization
+    // in one step.
+    Entity *make_entity(const int width, const int height, const int x, const int y, const std::string &name)
+    {
+      auto entity = entities.insert({name, Entity{width, height, x, y, name}});
+      return &(entity.first->second);
+    }
+
+    Entity *get_entity(const std::string &name)
+    {
+      return &entities.at(name);
+    }
+
+
+    // loop over all entities and all their updater function (if it exists)
+    void update_entities()
+    {
+      for (auto &entity : entities)
+      {
+        if (entity.second.updater) {
+          entity.second.updater(entity.second);
+        }
+      }
+    }
+
+
+  private:
+    // we cannot store the entities in a std::vector if we want to return a pointer to them,
+    // because a vector automatically resizing itself can invalidate the pointer that was returned.
+    // using a map guarantees that the memory assigned to the entity will never change, plus
+    // lets us easily look up an entity by name
+    std::map<std::string, Entity> entities;
+};
+
+int main()
+{
+  chaiscript::ChaiScript chai(chaiscript::Std_Lib::library());
+
+  chai.add(chaiscript::fun(&Entity::width), "width");
+  chai.add(chaiscript::fun(&Entity::height), "height");
+  chai.add(chaiscript::fun(&Entity::x), "x");
+  chai.add(chaiscript::fun(&Entity::y), "y");
+  chai.add(chaiscript::fun(&Entity::name), "name");
+  chai.add(chaiscript::fun(&Entity::updater), "updater");
+  chai.add(chaiscript::user_type<Entity>(), "Entity"); // this isn't strictly necessary but makes error messages nicer
+
+  chai.add(chaiscript::fun(&Factory::make_entity), "make_entity");
+  chai.add(chaiscript::fun(&Factory::get_entity), "get_entity");
+  chai.add(chaiscript::fun(&Factory::update_entities), "update_entities");
+  chai.add(chaiscript::user_type<Factory>(), "Factory"); // this isn't strictly necessary but makes error messages nicer
+
+
+  Factory f;
+  chai.add(chaiscript::var(&f), "f");
+
+  std::string script = R""(
+    f.make_entity(10,10,1,1,"entity1").updater = fun(e){ e.x += 1; e.y += 1 };
+    f.make_entity(10,10,10,10,"entity2").updater = fun(e){ e.x += 2; e.y += 2 };
+    f.make_entity(10,10,20,20,"entity3");
+
+    print(f.get_entity("entity1").x == 1)
+    print(f.get_entity("entity2").x == 10)
+    print(f.get_entity("entity3").x == 20)
+
+    f.update_entities(); // this runs the function objects we set in the previous lines
+    // we should now see the updated values
+
+    print(f.get_entity("entity1").x == 2)
+    print(f.get_entity("entity2").x == 12)
+    print(f.get_entity("entity3").x == 20) // this one has no updater, so it stays the same
+    )"";
+
+
+  chai.eval(script);
+
+
+
+}
+
+