Map function lambda functions C++. Demo factory method, polymorphism, lambda functions.

factory_method_lambda_functions.cpp

// Copyright 2016 Duc Hoang Bui, KAIST. All rights reserved.
// Licensed under MIT

#include <iostream>
#include <string>
#include <map>
#include <memory>
#include <functional>

struct Animal {
    virtual void Speak() {
        std::cout << "Animal speak\n";
    }
};

struct Cat : public Animal {
    virtual void Speak() override {
        std::cout << "Cat meo\n";
    }
};

struct Dog : public Animal {
    virtual void Speak() override {
        std::cout << "Dog bark\n";
    }
};

int main()
{
    
    std::map<std::string, std::function<std::unique_ptr<Animal>()>> test_map{
        {"animal", []() {return std::unique_ptr<Animal>(new Animal());} },
        {"cat", []() {return std::unique_ptr<Animal>(new Cat());} },
        {"dog", []() {return std::unique_ptr<Animal>(new Dog());} }
    };
    test_map["animal"]()->Speak();
    test_map["cat"]()->Speak();
    test_map["dog"]()->Speak();
}