Switched UIFrame and Scene to store their UIDrawables in shared_ptr to vector, instead of directly to vector. Every object that can be exposed to Python has to be safely shareable so it doesn't become a segfault, and that includes the UIDrawable collections AND the UIDrawable members. So we get the terrifying type for collections of child elements: 'std::shared_ptr<std::vector<std::shared_ptr<UIDrawable>>>'. May I be forgiven for my sins

src/GameEngine.cpp

@@ -121,7 +121,7 @@ void GameEngine::sUserInput()
     }
 }
 
-std::vector<std::shared_ptr<UIDrawable>>* GameEngine::scene_ui(std::string target)
+std::shared_ptr<std::vector<std::shared_ptr<UIDrawable>>> GameEngine::scene_ui(std::string target)
 {
     /* 
     // facts about maps
@@ -136,5 +136,5 @@ std::vector<std::shared_ptr<UIDrawable>>* GameEngine::scene_ui(std::string targe
     std::cout << "scenes[target]: " << (long)(scenes[target]) << std::endl;
     */
     if (scenes.count(target) == 0) return NULL;
-    return &scenes[target]->ui_elements;
+    return scenes[target]->ui_elements;
 }

src/GameEngine.h

@@ -42,6 +42,6 @@ public:
     std::vector<sf::SoundBuffer> sfxbuffers;
     sf::Music music;
     sf::Sound sfx;
-    std::vector<std::shared_ptr<UIDrawable>>* scene_ui(std::string scene);
+    std::shared_ptr<std::vector<std::shared_ptr<UIDrawable>>> scene_ui(std::string scene);
     
 };

src/Scene.cpp

@@ -1,7 +1,12 @@
 #include "Scene.h"
+#include "UI.h"
 
 //Scene::Scene() { game = 0; std::cout << "WARN: default Scene constructor called. (game = " << game << ")" << std::endl;};
-Scene::Scene(GameEngine* g) { game = g; }
+Scene::Scene(GameEngine* g)
+{
+    game = g; 
+    ui_elements = std::make_shared<std::vector<std::shared_ptr<UIDrawable>>>();
+}
 void Scene::registerAction(int code, std::string name)
 {
     actions[code] = name;

src/Scene.h

@@ -39,6 +39,6 @@ public:
     virtual bool registerActionInjected(int, std::string);
     virtual bool unregisterActionInjected(int, std::string);
     
-    std::vector<std::shared_ptr<UIDrawable>> ui_elements;
+    std::shared_ptr<std::vector<std::shared_ptr<UIDrawable>>> ui_elements;
 
 };

src/UI.cpp

@@ -10,6 +10,7 @@ void UIDrawable::render()
 UIFrame::UIFrame():
 x(0), y(0), w(0), h(0), outline(0)
 {
+    children = std::make_shared<std::vector<std::shared_ptr<UIDrawable>>>();
     /*
     pyOutlineColor = NULL;
     pyFillColor = NULL;
@@ -21,6 +22,7 @@ x(0), y(0), w(0), h(0), outline(0)
 UIFrame::UIFrame(float _x, float _y, float _w, float _h):
 x(_x), y(_y), w(_w), h(_h), outline(0)
 {
+    children = std::make_shared<std::vector<std::shared_ptr<UIDrawable>>>();
     /*
     pyOutlineColor = NULL;
     pyFillColor = NULL;
@@ -31,6 +33,7 @@ x(_x), y(_y), w(_w), h(_h), outline(0)
 
 UIFrame::~UIFrame()
 {
+    children.reset();
     /*
     if (pyOutlineColor) Py_DECREF(pyOutlineColor);
     else if (_outlineColor) delete _outlineColor;
@@ -64,7 +67,7 @@ void UIFrame::render(sf::Vector2f offset)
     //if (_outlineColor) { box.setOutlineColor(outlineColor()); }
     //box.setOutlineThickness(outline);
     //Resources::game->getWindow().draw(box);
-    for (auto drawable : children) {
+    for (auto drawable : *children) {
         drawable->render(offset + box.getPosition());
     }
 }

src/UI.h

@@ -38,7 +38,7 @@ public:
 
     //Simulate RectangleShape
     float x, y, w, h, outline;
-    std::vector<std::shared_ptr<UIDrawable>> children;
+    std::shared_ptr<std::vector<std::shared_ptr<UIDrawable>>> children;
     void render(sf::Vector2f) override final;
     void move(sf::Vector2f);
     
@@ -391,7 +391,7 @@ namespace mcrfpydef {
                 "outline=" << box.getOutlineThickness() << ", " << 
                 "fill_color=(" << (int)fc.r << ", " << (int)fc.g << ", " << (int)fc.b << ", " << (int)fc.a <<"), " <<
                 "outlinecolor=(" << (int)oc.r << ", " << (int)oc.g << ", " << (int)oc.b << ", " << (int)oc.a <<"), " <<
-                self->data->children.size() << " child" << (self->data->children.size() == 1 ? "" : "ren") <<  " objects" <<
+                self->data->children->size() << " child objects" <<
                 ")>";
         }
         std::string repr_str = ss.str();

src/UITestScene.cpp

@@ -13,6 +13,9 @@ UITestScene::UITestScene(GameEngine* g) : Scene(g)
     //registerAction(ActionCode::KEY + sf::Keyboard::Up, "up");
     //registerAction(ActionCode::KEY + sf::Keyboard::Down, "down");
     
+    // note - you can't use the pointer to UI elements in constructor.
+    // The scene map is still being assigned to, so this object can't be looked up. 
+    /*
     auto ui = Resources::game->scene_ui("uitest");
     if (ui)
     {
@@ -20,6 +23,7 @@ UITestScene::UITestScene(GameEngine* g) : Scene(g)
     } else {
         std::cout << "No UI vector was returned.\n";
     }
+    */
 
     // Create a UI element or three?
     auto e1 = std::make_shared<UIFrame>(100,150,400,400);
@@ -28,21 +32,21 @@ UITestScene::UITestScene(GameEngine* g) : Scene(g)
     e1->box.setFillColor(sf::Color(255, 0, 0));
     //e1.fillColor(sf::Color(255,0,0));
     //if (ui) ui->push_back(e1);
-    ui_elements.push_back(e1);
+    ui_elements->push_back(e1);
 
     auto e1a = std::make_shared<UIFrame>(50,50,200,200);
     e1a->box.setPosition(50, 50);
     e1a->box.setSize(sf::Vector2f(200,200));
     e1a->box.setFillColor(sf::Color(0, 255, 0));
     //e1a.fillColor(sf::Color(0, 255, 0));
-    e1->children.push_back(e1a);
+    e1->children->push_back(e1a);
     
     auto e1aa = std::make_shared<UIFrame>(5,5,100,100);
     e1aa->box.setPosition(5, 5);
     e1aa->box.setSize(sf::Vector2f(100,100));
     e1aa->box.setFillColor(sf::Color(0, 0, 255));
     //e1aa.fillColor(sf::Color(0, 0, 255));  
-    e1a->children.push_back(e1aa);
+    e1a->children->push_back(e1aa);
     
     auto e2 = std::make_shared<UICaption>();
     e2->text.setFont(game->getFont());
@@ -51,12 +55,16 @@ UITestScene::UITestScene(GameEngine* g) : Scene(g)
     e2->text.setPosition(50, 250);
     
     //if (ui) ui->push_back(e2);
-    ui_elements.push_back(e2);
+    ui_elements->push_back(e2);
     //ui_elements.push_back(&e1);
     //ui_elements.push_back(&e2);
    
+    /*
+    // note - you can't use the pointer to UI elements in constructor.
+    // The scene map is still being assigned to, so this object can't be looked up. 
     if (ui)
     std::cout << "pointer to ui_elements now shows size=" << ui->size() << std::endl;
+    */
 }
 
 void UITestScene::update()
@@ -87,7 +95,8 @@ void UITestScene::sRender()
     //for (auto e: ui_elements)
     //auto ui = Resources::game->scene_ui("uitest");
     //if (ui)
-    for (auto e: ui_elements)
+    auto vec = *ui_elements;
+    for (auto e: vec)
     {
         //std::cout << "Rendering element\n";
         if (e)