Factory method anti-if implementation

Question

I'm applying the Factory design pattern in my C++ project, and below you can see how I am doing it. I try to improve my code by following the "anti-if" campaign, thus want to remove the if statements that I am having. Any idea how can I do it?

typedef std::map<std::string, Chip*> ChipList;

Chip* ChipFactory::createChip(const std::string& type) {
    MCList::iterator existing = Chips.find(type);
    if (existing != Chips.end()) {
        return (existing->second);
    }
    if (type == "R500") {
        return Chips[type] = new ChipR500();
    }
    if (type == "PIC32F42") {
        return Chips[type] = new ChipPIC32F42();
    }
    if (type == "34HC22") {
        return Chips[type] = new Chip34HC22();
    }
    return 0;
}

I would imagine creating a map, with string as the key, and the constructor (or something to create the object). After that, I can just get the constructor from the map using the type (type are strings) and create my object without any if. (I know I'm being a bit paranoid, but I want to know if it can be done or not.)

Answer 1

struct Chip{
};

struct ChipR500 : Chip{};

struct PIC32F42 : Chip{};

struct ChipCreator{
   virtual Chip *make() = 0;
};

struct ChipR500Creator : ChipCreator{
   Chip *make(){return new ChipR500();}
};

struct PIC32F42Creator : ChipCreator{
   Chip *make(){return new PIC32F42();}
};

int main(){
   ChipR500Creator m;  // client code knows only the factory method interface, not the actuall concrete products
   Chip *p = m.make();
}

Answer 2

No you cannot get rid of the ifs. the createChip method creats a new instance depending on constant (type name )you pass as argument. but you may optimaze yuor code a little removing those 2 line out of if statment.

 microcontrollers[type] = newController;
 return microcontrollers[type];