Filling list inside object and accessing to it later - c++

Question

I'm sorry if the title isn't very explicit, but I'll try to explain it better. I'm not very familiar with c++ and I'm using openFrameworks for the first time. I'm trying to do something that's probably quite easy, at least in other languages it is, but I'm not being able to do it :(
I have a class Video and inside it I have an object list<ofImage> keyFrames; and several methods to interact with it like the following:
void addKeyFrame(ofImage img) {
if(keyFrames.size() == 0) {
keyFrames.push_front(img);
}
else {
keyFrames.push_back(img);
}
}
list<ofImage> * getKeyFrames() {
list<ofImage> *list = &keyFrames;
return list;
}
void clearKeyFrames() {
keyFrames.clear();
}
In other class I have several Video objects and I have a function that uses addKeyFrame(ofImage img) to fill the list for each object. In the end of that function if I print the list size it is greater than zero.
Inside draw() function I iterate each Video object and I try to draw each image inside their keyFrame list, but the list is always empty and I just filled it with images... I'm using getKeyFrames() function to return a pointer to the list. How can it be empty if I just added objects to it in another function and if I verified that the size was greater than zero? And if I try to debug the application I feel even more lost lol.
Please tell me if you need anymore information and if you know what I'm doing wrong. Thanks!

Answer 1

Ok, A few little things:
1- You shouldn't check for empty lists (or any other STL containers) like this:
if(keyFrames.size() == 0)
This is faster and more "stylish":
if(keyFrames.empty())
2- You've created an unnecessary variable here:
list<ofImage> * getKeyFrames() {
list<ofImage> *list = &keyFrames;
return list;
}
You could do just:
list<ofImage> * getKeyFrames() {
return &keyFrames;
}
3- Pointers are not (most times) the best solution in C++. A reference is the most used substitute, but it would be even better in htis case if you returned an iterator:
list<ofImage>::iterator GetBeginIterator() {
return keyFrames.begin();
}
This way you could use the iterator just like a pointer, increasing it to iterate trough the frames and dereferencing it (with * operator)...