Instantiate objects dynamically from an array of classes

[danep]

Basically, I want to create a series of objects dynamically in an arbitrary order. If I have Class1 and Class2 that both inherit from BaseClass, I want to do something like this: (obviously this will not function, but I think you'll get the point)

class list_of_classes[3] = {Class1, Class2, Class1};
int class_num = 0;

BaseClass * someObject = new list_of_classes[class_num];

void CreateNextClass()
{
delete someObject;
someObject = new list_of_classes[class_num];
class_num++;
}

To give some context, I am building a game where Class1, Class2, etc... are types of levels, and I want to be able to load the levels in an arbitrary order. I understand that I could just create an array of objects at compile time and cycle through them at run time, but this doesn't seem very efficient as the number of levels increases, nor does it seem object-oriented. Is there a way to do this, or do I need to take an entirely different approach? Thank you so much for any advice.

[Lindley]

You could use a factory pattern, eg:

BaseClass *CreateLevel(int type)
{
    switch(type)
    {
    case 0:
        return new LevelType0;
    case 1:
        return new LevelType1;
    // etc
}

[danep]

Ah, so that's what factory patterns are That looks like a pretty good solution. I'd prefer not to have to edit the factory just to add a new type of level, but this is at least more encapsulated than my current solution. Thanks for the tip.

[D_Drmmr]

Have a look at typelists. You'll probably want to get a hold of a copy of 'Modern C++ design' for some explanation.